| // Copyright 2009 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package runtime |
| |
| import ( |
| "internal/cpu" |
| "runtime/internal/atomic" |
| "runtime/internal/sys" |
| "unsafe" |
| ) |
| |
| // defined constants |
| const ( |
| // G status |
| // |
| // Beyond indicating the general state of a G, the G status |
| // acts like a lock on the goroutine's stack (and hence its |
| // ability to execute user code). |
| // |
| // If you add to this list, add to the list |
| // of "okay during garbage collection" status |
| // in mgcmark.go too. |
| // |
| // TODO(austin): The _Gscan bit could be much lighter-weight. |
| // For example, we could choose not to run _Gscanrunnable |
| // goroutines found in the run queue, rather than CAS-looping |
| // until they become _Grunnable. And transitions like |
| // _Gscanwaiting -> _Gscanrunnable are actually okay because |
| // they don't affect stack ownership. |
| |
| // _Gidle means this goroutine was just allocated and has not |
| // yet been initialized. |
| _Gidle = iota // 0 |
| |
| // _Grunnable means this goroutine is on a run queue. It is |
| // not currently executing user code. The stack is not owned. |
| _Grunnable // 1 |
| |
| // _Grunning means this goroutine may execute user code. The |
| // stack is owned by this goroutine. It is not on a run queue. |
| // It is assigned an M and a P (g.m and g.m.p are valid). |
| _Grunning // 2 |
| |
| // _Gsyscall means this goroutine is executing a system call. |
| // It is not executing user code. The stack is owned by this |
| // goroutine. It is not on a run queue. It is assigned an M. |
| _Gsyscall // 3 |
| |
| // _Gwaiting means this goroutine is blocked in the runtime. |
| // It is not executing user code. It is not on a run queue, |
| // but should be recorded somewhere (e.g., a channel wait |
| // queue) so it can be ready()d when necessary. The stack is |
| // not owned *except* that a channel operation may read or |
| // write parts of the stack under the appropriate channel |
| // lock. Otherwise, it is not safe to access the stack after a |
| // goroutine enters _Gwaiting (e.g., it may get moved). |
| _Gwaiting // 4 |
| |
| // _Gmoribund_unused is currently unused, but hardcoded in gdb |
| // scripts. |
| _Gmoribund_unused // 5 |
| |
| // _Gdead means this goroutine is currently unused. It may be |
| // just exited, on a free list, or just being initialized. It |
| // is not executing user code. It may or may not have a stack |
| // allocated. The G and its stack (if any) are owned by the M |
| // that is exiting the G or that obtained the G from the free |
| // list. |
| _Gdead // 6 |
| |
| // _Genqueue_unused is currently unused. |
| _Genqueue_unused // 7 |
| |
| // _Gcopystack means this goroutine's stack is being moved. It |
| // is not executing user code and is not on a run queue. The |
| // stack is owned by the goroutine that put it in _Gcopystack. |
| _Gcopystack // 8 |
| |
| // _Gpreempted means this goroutine stopped itself for a |
| // suspendG preemption. It is like _Gwaiting, but nothing is |
| // yet responsible for ready()ing it. Some suspendG must CAS |
| // the status to _Gwaiting to take responsibility for |
| // ready()ing this G. |
| _Gpreempted // 9 |
| |
| // _Gexitingsyscall means this goroutine is exiting from a |
| // system call. This is like _Gsyscall, but the GC should not |
| // scan its stack. Currently this is only used in exitsyscall0 |
| // as a transient state when it drops the G. |
| _Gexitingsyscall // 10 |
| |
| // _Gscan combined with one of the above states other than |
| // _Grunning indicates that GC is scanning the stack. The |
| // goroutine is not executing user code and the stack is owned |
| // by the goroutine that set the _Gscan bit. |
| // |
| // _Gscanrunning is different: it is used to briefly block |
| // state transitions while GC signals the G to scan its own |
| // stack. This is otherwise like _Grunning. |
| // |
| // atomicstatus&~Gscan gives the state the goroutine will |
| // return to when the scan completes. |
| _Gscan = 0x1000 |
| _Gscanrunnable = _Gscan + _Grunnable // 0x1001 |
| _Gscanrunning = _Gscan + _Grunning // 0x1002 |
| _Gscansyscall = _Gscan + _Gsyscall // 0x1003 |
| _Gscanwaiting = _Gscan + _Gwaiting // 0x1004 |
| _Gscanpreempted = _Gscan + _Gpreempted // 0x1009 |
| ) |
| |
| const ( |
| // P status |
| |
| // _Pidle means a P is not being used to run user code or the |
| // scheduler. Typically, it's on the idle P list and available |
| // to the scheduler, but it may just be transitioning between |
| // other states. |
| // |
| // The P is owned by the idle list or by whatever is |
| // transitioning its state. Its run queue is empty. |
| _Pidle = iota |
| |
| // _Prunning means a P is owned by an M and is being used to |
| // run user code or the scheduler. Only the M that owns this P |
| // is allowed to change the P's status from _Prunning. The M |
| // may transition the P to _Pidle (if it has no more work to |
| // do), _Psyscall (when entering a syscall), or _Pgcstop (to |
| // halt for the GC). The M may also hand ownership of the P |
| // off directly to another M (e.g., to schedule a locked G). |
| _Prunning |
| |
| // _Psyscall means a P is not running user code. It has |
| // affinity to an M in a syscall but is not owned by it and |
| // may be stolen by another M. This is similar to _Pidle but |
| // uses lightweight transitions and maintains M affinity. |
| // |
| // Leaving _Psyscall must be done with a CAS, either to steal |
| // or retake the P. Note that there's an ABA hazard: even if |
| // an M successfully CASes its original P back to _Prunning |
| // after a syscall, it must understand the P may have been |
| // used by another M in the interim. |
| _Psyscall |
| |
| // _Pgcstop means a P is halted for STW and owned by the M |
| // that stopped the world. The M that stopped the world |
| // continues to use its P, even in _Pgcstop. Transitioning |
| // from _Prunning to _Pgcstop causes an M to release its P and |
| // park. |
| // |
| // The P retains its run queue and startTheWorld will restart |
| // the scheduler on Ps with non-empty run queues. |
| _Pgcstop |
| |
| // _Pdead means a P is no longer used (GOMAXPROCS shrank). We |
| // reuse Ps if GOMAXPROCS increases. A dead P is mostly |
| // stripped of its resources, though a few things remain |
| // (e.g., trace buffers). |
| _Pdead |
| ) |
| |
| // Mutual exclusion locks. In the uncontended case, |
| // as fast as spin locks (just a few user-level instructions), |
| // but on the contention path they sleep in the kernel. |
| // A zeroed Mutex is unlocked (no need to initialize each lock). |
| // Initialization is helpful for static lock ranking, but not required. |
| type mutex struct { |
| // Empty struct if lock ranking is disabled, otherwise includes the lock rank |
| lockRankStruct |
| // Futex-based impl treats it as uint32 key, |
| // while sema-based impl as M* waitm. |
| // Used to be a union, but unions break precise GC. |
| key uintptr |
| } |
| |
| // sleep and wakeup on one-time events. |
| // before any calls to notesleep or notewakeup, |
| // must call noteclear to initialize the Note. |
| // then, exactly one thread can call notesleep |
| // and exactly one thread can call notewakeup (once). |
| // once notewakeup has been called, the notesleep |
| // will return. future notesleep will return immediately. |
| // subsequent noteclear must be called only after |
| // previous notesleep has returned, e.g. it's disallowed |
| // to call noteclear straight after notewakeup. |
| // |
| // notetsleep is like notesleep but wakes up after |
| // a given number of nanoseconds even if the event |
| // has not yet happened. if a goroutine uses notetsleep to |
| // wake up early, it must wait to call noteclear until it |
| // can be sure that no other goroutine is calling |
| // notewakeup. |
| // |
| // notesleep/notetsleep are generally called on g0, |
| // notetsleepg is similar to notetsleep but is called on user g. |
| type note struct { |
| // Futex-based impl treats it as uint32 key, |
| // while sema-based impl as M* waitm. |
| // Used to be a union, but unions break precise GC. |
| key uintptr |
| } |
| |
| type funcval struct { |
| fn uintptr |
| // variable-size, fn-specific data here |
| } |
| |
| // The representation of a non-empty interface. |
| // See comment in iface.go for more details on this struct. |
| type iface struct { |
| tab unsafe.Pointer |
| data unsafe.Pointer |
| } |
| |
| // The representation of an empty interface. |
| // See comment in iface.go for more details on this struct. |
| type eface struct { |
| _type *_type |
| data unsafe.Pointer |
| } |
| |
| func efaceOf(ep *interface{}) *eface { |
| return (*eface)(unsafe.Pointer(ep)) |
| } |
| |
| // The guintptr, muintptr, and puintptr are all used to bypass write barriers. |
| // It is particularly important to avoid write barriers when the current P has |
| // been released, because the GC thinks the world is stopped, and an |
| // unexpected write barrier would not be synchronized with the GC, |
| // which can lead to a half-executed write barrier that has marked the object |
| // but not queued it. If the GC skips the object and completes before the |
| // queuing can occur, it will incorrectly free the object. |
| // |
| // We tried using special assignment functions invoked only when not |
| // holding a running P, but then some updates to a particular memory |
| // word went through write barriers and some did not. This breaks the |
| // write barrier shadow checking mode, and it is also scary: better to have |
| // a word that is completely ignored by the GC than to have one for which |
| // only a few updates are ignored. |
| // |
| // Gs and Ps are always reachable via true pointers in the |
| // allgs and allp lists or (during allocation before they reach those lists) |
| // from stack variables. |
| // |
| // Ms are always reachable via true pointers either from allm or |
| // freem. Unlike Gs and Ps we do free Ms, so it's important that |
| // nothing ever hold an muintptr across a safe point. |
| |
| // A guintptr holds a goroutine pointer, but typed as a uintptr |
| // to bypass write barriers. It is used in the Gobuf goroutine state |
| // and in scheduling lists that are manipulated without a P. |
| // |
| // The Gobuf.g goroutine pointer is almost always updated by assembly code. |
| // In one of the few places it is updated by Go code - func save - it must be |
| // treated as a uintptr to avoid a write barrier being emitted at a bad time. |
| // Instead of figuring out how to emit the write barriers missing in the |
| // assembly manipulation, we change the type of the field to uintptr, |
| // so that it does not require write barriers at all. |
| // |
| // Goroutine structs are published in the allg list and never freed. |
| // That will keep the goroutine structs from being collected. |
| // There is never a time that Gobuf.g's contain the only references |
| // to a goroutine: the publishing of the goroutine in allg comes first. |
| // Goroutine pointers are also kept in non-GC-visible places like TLS, |
| // so I can't see them ever moving. If we did want to start moving data |
| // in the GC, we'd need to allocate the goroutine structs from an |
| // alternate arena. Using guintptr doesn't make that problem any worse. |
| type guintptr uintptr |
| |
| //go:nosplit |
| func (gp guintptr) ptr() *g { return (*g)(unsafe.Pointer(gp)) } |
| |
| //go:nosplit |
| func (gp *guintptr) set(g *g) { *gp = guintptr(unsafe.Pointer(g)) } |
| |
| //go:nosplit |
| func (gp *guintptr) cas(old, new guintptr) bool { |
| return atomic.Casuintptr((*uintptr)(unsafe.Pointer(gp)), uintptr(old), uintptr(new)) |
| } |
| |
| // setGNoWB performs *gp = new without a write barrier. |
| // For times when it's impractical to use a guintptr. |
| //go:nosplit |
| //go:nowritebarrier |
| func setGNoWB(gp **g, new *g) { |
| (*guintptr)(unsafe.Pointer(gp)).set(new) |
| } |
| |
| type puintptr uintptr |
| |
| //go:nosplit |
| func (pp puintptr) ptr() *p { return (*p)(unsafe.Pointer(pp)) } |
| |
| //go:nosplit |
| func (pp *puintptr) set(p *p) { *pp = puintptr(unsafe.Pointer(p)) } |
| |
| // muintptr is a *m that is not tracked by the garbage collector. |
| // |
| // Because we do free Ms, there are some additional constrains on |
| // muintptrs: |
| // |
| // 1. Never hold an muintptr locally across a safe point. |
| // |
| // 2. Any muintptr in the heap must be owned by the M itself so it can |
| // ensure it is not in use when the last true *m is released. |
| type muintptr uintptr |
| |
| //go:nosplit |
| func (mp muintptr) ptr() *m { return (*m)(unsafe.Pointer(mp)) } |
| |
| //go:nosplit |
| func (mp *muintptr) set(m *m) { *mp = muintptr(unsafe.Pointer(m)) } |
| |
| // setMNoWB performs *mp = new without a write barrier. |
| // For times when it's impractical to use an muintptr. |
| //go:nosplit |
| //go:nowritebarrier |
| func setMNoWB(mp **m, new *m) { |
| (*muintptr)(unsafe.Pointer(mp)).set(new) |
| } |
| |
| // sudog represents a g in a wait list, such as for sending/receiving |
| // on a channel. |
| // |
| // sudog is necessary because the g ↔ synchronization object relation |
| // is many-to-many. A g can be on many wait lists, so there may be |
| // many sudogs for one g; and many gs may be waiting on the same |
| // synchronization object, so there may be many sudogs for one object. |
| // |
| // sudogs are allocated from a special pool. Use acquireSudog and |
| // releaseSudog to allocate and free them. |
| type sudog struct { |
| // The following fields are protected by the hchan.lock of the |
| // channel this sudog is blocking on. shrinkstack depends on |
| // this for sudogs involved in channel ops. |
| |
| g *g |
| |
| next *sudog |
| prev *sudog |
| elem unsafe.Pointer // data element (may point to stack) |
| |
| // The following fields are never accessed concurrently. |
| // For channels, waitlink is only accessed by g. |
| // For semaphores, all fields (including the ones above) |
| // are only accessed when holding a semaRoot lock. |
| |
| acquiretime int64 |
| releasetime int64 |
| ticket uint32 |
| |
| // isSelect indicates g is participating in a select, so |
| // g.selectDone must be CAS'd to win the wake-up race. |
| isSelect bool |
| |
| // success indicates whether communication over channel c |
| // succeeded. It is true if the goroutine was awoken because a |
| // value was delivered over channel c, and false if awoken |
| // because c was closed. |
| success bool |
| |
| parent *sudog // semaRoot binary tree |
| waitlink *sudog // g.waiting list or semaRoot |
| waittail *sudog // semaRoot |
| c *hchan // channel |
| } |
| |
| /* |
| Not used by gccgo. |
| |
| type libcall struct { |
| fn uintptr |
| n uintptr // number of parameters |
| args uintptr // parameters |
| r1 uintptr // return values |
| r2 uintptr |
| err uintptr // error number |
| } |
| |
| // Stack describes a Go execution stack. |
| // The bounds of the stack are exactly [lo, hi), |
| // with no implicit data structures on either side. |
| type stack struct { |
| lo uintptr |
| hi uintptr |
| } |
| */ |
| |
| // heldLockInfo gives info on a held lock and the rank of that lock |
| type heldLockInfo struct { |
| lockAddr uintptr |
| rank lockRank |
| } |
| |
| type g struct { |
| // Stack parameters. |
| // stack describes the actual stack memory: [stack.lo, stack.hi). |
| // stackguard0 is the stack pointer compared in the Go stack growth prologue. |
| // It is stack.lo+StackGuard normally, but can be StackPreempt to trigger a preemption. |
| // stackguard1 is the stack pointer compared in the C stack growth prologue. |
| // It is stack.lo+StackGuard on g0 and gsignal stacks. |
| // It is ~0 on other goroutine stacks, to trigger a call to morestackc (and crash). |
| // Not for gccgo: stack stack // offset known to runtime/cgo |
| // Not for gccgo: stackguard0 uintptr // offset known to liblink |
| // Not for gccgo: stackguard1 uintptr // offset known to liblink |
| |
| _panic *_panic // innermost panic - offset known to liblink |
| _defer *_defer // innermost defer |
| m *m // current m; offset known to arm liblink |
| // Not for gccgo: sched gobuf |
| syscallsp uintptr // if status==Gsyscall, syscallsp = sched.sp to use during gc |
| syscallpc uintptr // if status==Gsyscall, syscallpc = sched.pc to use during gc |
| // Not for gccgo: stktopsp uintptr // expected sp at top of stack, to check in traceback |
| param unsafe.Pointer // passed parameter on wakeup |
| atomicstatus uint32 |
| // Not for gccgo: stackLock uint32 // sigprof/scang lock; TODO: fold in to atomicstatus |
| goid int64 |
| schedlink guintptr |
| waitsince int64 // approx time when the g become blocked |
| waitreason waitReason // if status==Gwaiting |
| preempt bool // preemption signal, duplicates stackguard0 = stackpreempt |
| preemptStop bool // transition to _Gpreempted on preemption; otherwise, just deschedule |
| // Not for gccgo: preemptShrink bool // shrink stack at synchronous safe point |
| // asyncSafePoint is set if g is stopped at an asynchronous |
| // safe point. This means there are frames on the stack |
| // without precise pointer information. |
| asyncSafePoint bool |
| |
| paniconfault bool // panic (instead of crash) on unexpected fault address |
| preemptscan bool // preempted g does scan for gc |
| gcscandone bool // g has scanned stack; protected by _Gscan bit in status |
| throwsplit bool // must not split stack |
| |
| gcScannedSyscallStack bool // gccgo specific; see scanSyscallStack |
| |
| // activeStackChans indicates that there are unlocked channels |
| // pointing into this goroutine's stack. If true, stack |
| // copying needs to acquire channel locks to protect these |
| // areas of the stack. |
| activeStackChans bool |
| // parkingOnChan indicates that the goroutine is about to |
| // park on a chansend or chanrecv. Used to signal an unsafe point |
| // for stack shrinking. It's a boolean value, but is updated atomically. |
| parkingOnChan uint8 |
| |
| raceignore int8 // ignore race detection events |
| sysblocktraced bool // StartTrace has emitted EvGoInSyscall about this goroutine |
| sysexitticks int64 // cputicks when syscall has returned (for tracing) |
| traceseq uint64 // trace event sequencer |
| tracelastp puintptr // last P emitted an event for this goroutine |
| lockedm muintptr |
| sig uint32 |
| writebuf []byte |
| sigcode0 uintptr |
| sigcode1 uintptr |
| sigpc uintptr |
| gopc uintptr // pc of go statement that created this goroutine |
| ancestors *[]ancestorInfo // ancestor information goroutine(s) that created this goroutine (only used if debug.tracebackancestors) |
| startpc uintptr // pc of goroutine function |
| // Not for gccgo: racectx uintptr |
| waiting *sudog // sudog structures this g is waiting on (that have a valid elem ptr); in lock order |
| // Not for gccgo: cgoCtxt []uintptr // cgo traceback context |
| labels unsafe.Pointer // profiler labels |
| timer *timer // cached timer for time.Sleep |
| selectDone uint32 // are we participating in a select and did someone win the race? |
| |
| // Per-G GC state |
| |
| // gcAssistBytes is this G's GC assist credit in terms of |
| // bytes allocated. If this is positive, then the G has credit |
| // to allocate gcAssistBytes bytes without assisting. If this |
| // is negative, then the G must correct this by performing |
| // scan work. We track this in bytes to make it fast to update |
| // and check for debt in the malloc hot path. The assist ratio |
| // determines how this corresponds to scan work debt. |
| gcAssistBytes int64 |
| |
| // Remaining fields are specific to gccgo. |
| |
| exception unsafe.Pointer // current exception being thrown |
| isforeign bool // whether current exception is not from Go |
| |
| // When using split-stacks, these fields holds the results of |
| // __splitstack_find while executing a syscall. These are used |
| // by the garbage collector to scan the goroutine's stack. |
| // |
| // When not using split-stacks, g0 stacks are allocated by the |
| // libc and other goroutine stacks are allocated by malg. |
| // gcstack: unused (sometimes cleared) |
| // gcstacksize: g0: 0; others: size of stack |
| // gcnextsegment: unused |
| // gcnextsp: current SP while executing a syscall |
| // gcinitialsp: g0: top of stack; others: start of stack memory |
| // gcnextsp2: current secondary stack pointer (if present) |
| // gcinitialsp2: start of secondary stack (if present) |
| gcstack uintptr |
| gcstacksize uintptr |
| gcnextsegment uintptr |
| gcnextsp uintptr |
| gcinitialsp unsafe.Pointer |
| gcnextsp2 uintptr |
| gcinitialsp2 unsafe.Pointer |
| |
| // gcregs holds the register values while executing a syscall. |
| // This is set by getcontext and scanned by the garbage collector. |
| gcregs g_ucontext_t |
| |
| entry func(unsafe.Pointer) // goroutine function to run |
| entryfn uintptr // function address passed to __go_go |
| entrysp uintptr // the stack pointer of the outermost Go frame |
| fromgogo bool // whether entered from gogo function |
| |
| scanningself bool // whether goroutine is scanning its own stack |
| |
| scang uintptr // the g that wants to scan this g's stack (uintptr to avoid write barrier) |
| scangcw uintptr // gc worker for scanning stack (uintptr to avoid write barrier) |
| |
| isSystemGoroutine bool // whether goroutine is a "system" goroutine |
| isFinalizerGoroutine bool // whether goroutine is the finalizer goroutine |
| |
| deferring bool // whether we are running a deferred function |
| goexiting bool // whether we are running Goexit |
| ranCgocallBackDone bool // whether we deferred CgocallBackDone |
| |
| traceback uintptr // stack traceback buffer |
| |
| context g_ucontext_t // saved context for setcontext |
| stackcontext [10]uintptr // split-stack context |
| } |
| |
| type m struct { |
| g0 *g // goroutine with scheduling stack |
| // Not for gccgo: morebuf gobuf // gobuf arg to morestack |
| // Not for gccgo: divmod uint32 // div/mod denominator for arm - known to liblink |
| |
| // Fields not known to debuggers. |
| procid uint64 // for debuggers, but offset not hard-coded |
| gsignal *g // signal-handling g |
| // Not for gccgo: goSigStack gsignalStack // Go-allocated signal handling stack |
| sigmask sigset // storage for saved signal mask |
| // Not for gccgo: tls [6]uintptr // thread-local storage (for x86 extern register) |
| mstartfn func() |
| curg *g // current running goroutine |
| caughtsig guintptr // goroutine running during fatal signal |
| p puintptr // attached p for executing go code (nil if not executing go code) |
| nextp puintptr |
| oldp puintptr // the p that was attached before executing a syscall |
| id int64 |
| mallocing int32 |
| throwing int32 |
| preemptoff string // if != "", keep curg running on this m |
| locks int32 |
| softfloat int32 |
| dying int32 |
| profilehz int32 |
| spinning bool // m is out of work and is actively looking for work |
| blocked bool // m is blocked on a note |
| newSigstack bool // minit on C thread called sigaltstack |
| printlock int8 |
| incgo bool // m is executing a cgo call |
| freeWait uint32 // if == 0, safe to free g0 and delete m (atomic) |
| fastrand [2]uint32 |
| needextram bool |
| traceback uint8 |
| ncgocall uint64 // number of cgo calls in total |
| ncgo int32 // number of cgo calls currently in progress |
| // Not for gccgo: cgoCallersUse uint32 // if non-zero, cgoCallers in use temporarily |
| // Not for gccgo: cgoCallers *cgoCallers // cgo traceback if crashing in cgo call |
| doesPark bool // non-P running threads: sysmon and newmHandoff never use .park |
| park note |
| alllink *m // on allm |
| schedlink muintptr |
| lockedg guintptr |
| createstack [32]location // stack that created this thread. |
| lockedExt uint32 // tracking for external LockOSThread |
| lockedInt uint32 // tracking for internal lockOSThread |
| nextwaitm muintptr // next m waiting for lock |
| waitunlockf func(*g, unsafe.Pointer) bool |
| waitlock unsafe.Pointer |
| waittraceev byte |
| waittraceskip int |
| startingtrace bool |
| syscalltick uint32 |
| freelink *m // on sched.freem |
| |
| // mFixup is used to synchronize OS related m state (credentials etc) |
| // use mutex to access. |
| mFixup struct { |
| lock mutex |
| fn func(bool) bool |
| } |
| |
| // these are here because they are too large to be on the stack |
| // of low-level NOSPLIT functions. |
| // Not for gccgo: libcall libcall |
| // Not for gccgo: libcallpc uintptr // for cpu profiler |
| // Not for gccgo: libcallsp uintptr |
| // Not for gccgo: libcallg guintptr |
| // Not for gccgo: syscall libcall // stores syscall parameters on windows |
| |
| // preemptGen counts the number of completed preemption |
| // signals. This is used to detect when a preemption is |
| // requested, but fails. Accessed atomically. |
| preemptGen uint32 |
| |
| // Whether this is a pending preemption signal on this M. |
| // Accessed atomically. |
| signalPending uint32 |
| |
| dlogPerM |
| |
| mOS |
| |
| // Up to 10 locks held by this m, maintained by the lock ranking code. |
| locksHeldLen int |
| locksHeld [10]heldLockInfo |
| |
| // Remaining fields are specific to gccgo. |
| |
| gsignalstack unsafe.Pointer // stack for gsignal |
| gsignalstacksize uintptr |
| |
| dropextram bool // drop after call is done |
| exiting bool // thread is exiting |
| |
| scannote note // synchonization for signal-based stack scanning |
| } |
| |
| type p struct { |
| id int32 |
| status uint32 // one of pidle/prunning/... |
| link puintptr |
| schedtick uint32 // incremented on every scheduler call |
| syscalltick uint32 // incremented on every system call |
| sysmontick sysmontick // last tick observed by sysmon |
| m muintptr // back-link to associated m (nil if idle) |
| mcache *mcache |
| pcache pageCache |
| raceprocctx uintptr |
| |
| // gccgo has only one size of defer. |
| deferpool []*_defer |
| deferpoolbuf [32]*_defer |
| |
| // Cache of goroutine ids, amortizes accesses to runtime·sched.goidgen. |
| goidcache uint64 |
| goidcacheend uint64 |
| |
| // Queue of runnable goroutines. Accessed without lock. |
| runqhead uint32 |
| runqtail uint32 |
| runq [256]guintptr |
| // runnext, if non-nil, is a runnable G that was ready'd by |
| // the current G and should be run next instead of what's in |
| // runq if there's time remaining in the running G's time |
| // slice. It will inherit the time left in the current time |
| // slice. If a set of goroutines is locked in a |
| // communicate-and-wait pattern, this schedules that set as a |
| // unit and eliminates the (potentially large) scheduling |
| // latency that otherwise arises from adding the ready'd |
| // goroutines to the end of the run queue. |
| runnext guintptr |
| |
| // Available G's (status == Gdead) |
| gFree struct { |
| gList |
| n int32 |
| } |
| |
| sudogcache []*sudog |
| sudogbuf [128]*sudog |
| |
| // Cache of mspan objects from the heap. |
| mspancache struct { |
| // We need an explicit length here because this field is used |
| // in allocation codepaths where write barriers are not allowed, |
| // and eliminating the write barrier/keeping it eliminated from |
| // slice updates is tricky, moreso than just managing the length |
| // ourselves. |
| len int |
| buf [128]*mspan |
| } |
| |
| tracebuf traceBufPtr |
| |
| // traceSweep indicates the sweep events should be traced. |
| // This is used to defer the sweep start event until a span |
| // has actually been swept. |
| traceSweep bool |
| // traceSwept and traceReclaimed track the number of bytes |
| // swept and reclaimed by sweeping in the current sweep loop. |
| traceSwept, traceReclaimed uintptr |
| |
| palloc persistentAlloc // per-P to avoid mutex |
| |
| _ uint32 // Alignment for atomic fields below |
| |
| // The when field of the first entry on the timer heap. |
| // This is updated using atomic functions. |
| // This is 0 if the timer heap is empty. |
| timer0When uint64 |
| |
| // The earliest known nextwhen field of a timer with |
| // timerModifiedEarlier status. Because the timer may have been |
| // modified again, there need not be any timer with this value. |
| // This is updated using atomic functions. |
| // This is 0 if the value is unknown. |
| timerModifiedEarliest uint64 |
| |
| // Per-P GC state |
| gcAssistTime int64 // Nanoseconds in assistAlloc |
| gcFractionalMarkTime int64 // Nanoseconds in fractional mark worker (atomic) |
| |
| // gcMarkWorkerMode is the mode for the next mark worker to run in. |
| // That is, this is used to communicate with the worker goroutine |
| // selected for immediate execution by |
| // gcController.findRunnableGCWorker. When scheduling other goroutines, |
| // this field must be set to gcMarkWorkerNotWorker. |
| gcMarkWorkerMode gcMarkWorkerMode |
| // gcMarkWorkerStartTime is the nanotime() at which the most recent |
| // mark worker started. |
| gcMarkWorkerStartTime int64 |
| |
| // gcw is this P's GC work buffer cache. The work buffer is |
| // filled by write barriers, drained by mutator assists, and |
| // disposed on certain GC state transitions. |
| gcw gcWork |
| |
| // wbBuf is this P's GC write barrier buffer. |
| // |
| // TODO: Consider caching this in the running G. |
| wbBuf wbBuf |
| |
| runSafePointFn uint32 // if 1, run sched.safePointFn at next safe point |
| |
| // statsSeq is a counter indicating whether this P is currently |
| // writing any stats. Its value is even when not, odd when it is. |
| statsSeq uint32 |
| |
| // Lock for timers. We normally access the timers while running |
| // on this P, but the scheduler can also do it from a different P. |
| timersLock mutex |
| |
| // Actions to take at some time. This is used to implement the |
| // standard library's time package. |
| // Must hold timersLock to access. |
| timers []*timer |
| |
| // Number of timers in P's heap. |
| // Modified using atomic instructions. |
| numTimers uint32 |
| |
| // Number of timerModifiedEarlier timers on P's heap. |
| // This should only be modified while holding timersLock, |
| // or while the timer status is in a transient state |
| // such as timerModifying. |
| adjustTimers uint32 |
| |
| // Number of timerDeleted timers in P's heap. |
| // Modified using atomic instructions. |
| deletedTimers uint32 |
| |
| // Race context used while executing timer functions. |
| // Not for gccgo: timerRaceCtx uintptr |
| |
| // preempt is set to indicate that this P should be enter the |
| // scheduler ASAP (regardless of what G is running on it). |
| preempt bool |
| |
| pad cpu.CacheLinePad |
| } |
| |
| type schedt struct { |
| // accessed atomically. keep at top to ensure alignment on 32-bit systems. |
| goidgen uint64 |
| lastpoll uint64 // time of last network poll, 0 if currently polling |
| pollUntil uint64 // time to which current poll is sleeping |
| |
| lock mutex |
| |
| // When increasing nmidle, nmidlelocked, nmsys, or nmfreed, be |
| // sure to call checkdead(). |
| |
| midle muintptr // idle m's waiting for work |
| nmidle int32 // number of idle m's waiting for work |
| nmidlelocked int32 // number of locked m's waiting for work |
| mnext int64 // number of m's that have been created and next M ID |
| maxmcount int32 // maximum number of m's allowed (or die) |
| nmsys int32 // number of system m's not counted for deadlock |
| nmfreed int64 // cumulative number of freed m's |
| |
| ngsys uint32 // number of system goroutines; updated atomically |
| |
| pidle puintptr // idle p's |
| npidle uint32 |
| nmspinning uint32 // See "Worker thread parking/unparking" comment in proc.go. |
| |
| // Global runnable queue. |
| runq gQueue |
| runqsize int32 |
| |
| // disable controls selective disabling of the scheduler. |
| // |
| // Use schedEnableUser to control this. |
| // |
| // disable is protected by sched.lock. |
| disable struct { |
| // user disables scheduling of user goroutines. |
| user bool |
| runnable gQueue // pending runnable Gs |
| n int32 // length of runnable |
| } |
| |
| // Global cache of dead G's. |
| gFree struct { |
| lock mutex |
| list gList // Gs |
| n int32 |
| } |
| |
| // Central cache of sudog structs. |
| sudoglock mutex |
| sudogcache *sudog |
| |
| // Central pool of available defer structs. |
| deferlock mutex |
| deferpool *_defer |
| |
| // freem is the list of m's waiting to be freed when their |
| // m.exited is set. Linked through m.freelink. |
| freem *m |
| |
| gcwaiting uint32 // gc is waiting to run |
| stopwait int32 |
| stopnote note |
| sysmonwait uint32 |
| sysmonnote note |
| |
| // While true, sysmon not ready for mFixup calls. |
| // Accessed atomically. |
| sysmonStarting uint32 |
| |
| // safepointFn should be called on each P at the next GC |
| // safepoint if p.runSafePointFn is set. |
| safePointFn func(*p) |
| safePointWait int32 |
| safePointNote note |
| |
| profilehz int32 // cpu profiling rate |
| |
| procresizetime int64 // nanotime() of last change to gomaxprocs |
| totaltime int64 // ∫gomaxprocs dt up to procresizetime |
| |
| // sysmonlock protects sysmon's actions on the runtime. |
| // |
| // Acquire and hold this mutex to block sysmon from interacting |
| // with the rest of the runtime. |
| sysmonlock mutex |
| } |
| |
| // Values for the flags field of a sigTabT. |
| const ( |
| _SigNotify = 1 << iota // let signal.Notify have signal, even if from kernel |
| _SigKill // if signal.Notify doesn't take it, exit quietly |
| _SigThrow // if signal.Notify doesn't take it, exit loudly |
| _SigPanic // if the signal is from the kernel, panic |
| _SigDefault // if the signal isn't explicitly requested, don't monitor it |
| _SigGoExit // cause all runtime procs to exit (only used on Plan 9). |
| _SigSetStack // add SA_ONSTACK to libc handler |
| _SigUnblock // always unblock; see blockableSig |
| _SigIgn // _SIG_DFL action is to ignore the signal |
| ) |
| |
| // Lock-free stack node. |
| // Also known to export_test.go. |
| type lfnode struct { |
| next uint64 |
| pushcnt uintptr |
| } |
| |
| type forcegcstate struct { |
| lock mutex |
| g *g |
| idle uint32 |
| } |
| |
| // startupRandomData holds random bytes initialized at startup. These come from |
| // the ELF AT_RANDOM auxiliary vector. |
| var startupRandomData []byte |
| |
| // extendRandom extends the random numbers in r[:n] to the whole slice r. |
| // Treats n<0 as n==0. |
| func extendRandom(r []byte, n int) { |
| if n < 0 { |
| n = 0 |
| } |
| for n < len(r) { |
| // Extend random bits using hash function & time seed |
| w := n |
| if w > 16 { |
| w = 16 |
| } |
| h := memhash(unsafe.Pointer(&r[n-w]), uintptr(nanotime()), uintptr(w)) |
| for i := 0; i < sys.PtrSize && n < len(r); i++ { |
| r[n] = byte(h) |
| n++ |
| h >>= 8 |
| } |
| } |
| } |
| |
| // A _defer holds an entry on the list of deferred calls. |
| // If you add a field here, add code to clear it in freedefer. |
| // This struct must match the code in Defer_statement::defer_struct_type |
| // in the compiler. |
| // Some defers will be allocated on the stack and some on the heap. |
| // All defers are logically part of the stack, so write barriers to |
| // initialize them are not required. All defers must be manually scanned, |
| // and for heap defers, marked. |
| type _defer struct { |
| // The next entry in the stack. |
| link *_defer |
| |
| // The stack variable for the function which called this defer |
| // statement. This is set to true if we are returning from |
| // that function, false if we are panicing through it. |
| frame *bool |
| |
| // The value of the panic stack when this function is |
| // deferred. This function can not recover this value from |
| // the panic stack. This can happen if a deferred function |
| // has a defer statement itself. |
| panicStack *_panic |
| |
| // The panic that caused the defer to run. This is used to |
| // discard panics that have already been handled. |
| _panic *_panic |
| |
| // The function to call. |
| pfn uintptr |
| |
| // The argument to pass to the function. |
| arg unsafe.Pointer |
| |
| // The return address that a recover thunk matches against. |
| // This is set by __go_set_defer_retaddr which is called by |
| // the thunks created by defer statements. |
| retaddr uintptr |
| |
| // Set to true if a function created by reflect.MakeFunc is |
| // permitted to recover. The return address of such a |
| // function function will be somewhere in libffi, so __retaddr |
| // is not useful. |
| makefunccanrecover bool |
| |
| // Whether the _defer is heap allocated. |
| heap bool |
| } |
| |
| // panics |
| // This is the gccgo version. |
| type _panic struct { |
| // The next entry in the stack. |
| link *_panic |
| |
| // The value associated with this panic. |
| arg interface{} |
| |
| // Whether this panic has been recovered. |
| recovered bool |
| |
| // Whether this panic was pushed on the stack because of an |
| // exception thrown in some other language. |
| isforeign bool |
| |
| // Whether this panic was already seen by a deferred function |
| // which called panic again. |
| aborted bool |
| |
| // Whether this panic was created for goexit. |
| goexit bool |
| } |
| |
| // ancestorInfo records details of where a goroutine was started. |
| type ancestorInfo struct { |
| pcs []uintptr // pcs from the stack of this goroutine |
| goid int64 // goroutine id of this goroutine; original goroutine possibly dead |
| gopc uintptr // pc of go statement that created this goroutine |
| } |
| |
| const ( |
| _TraceRuntimeFrames = 1 << iota // include frames for internal runtime functions. |
| _TraceTrap // the initial PC, SP are from a trap, not a return PC from a call |
| _TraceJumpStack // if traceback is on a systemstack, resume trace at g that called into it |
| ) |
| |
| // The maximum number of frames we print for a traceback |
| const _TracebackMaxFrames = 100 |
| |
| // A waitReason explains why a goroutine has been stopped. |
| // See gopark. Do not re-use waitReasons, add new ones. |
| type waitReason uint8 |
| |
| const ( |
| waitReasonZero waitReason = iota // "" |
| waitReasonGCAssistMarking // "GC assist marking" |
| waitReasonIOWait // "IO wait" |
| waitReasonChanReceiveNilChan // "chan receive (nil chan)" |
| waitReasonChanSendNilChan // "chan send (nil chan)" |
| waitReasonDumpingHeap // "dumping heap" |
| waitReasonGarbageCollection // "garbage collection" |
| waitReasonGarbageCollectionScan // "garbage collection scan" |
| waitReasonPanicWait // "panicwait" |
| waitReasonSelect // "select" |
| waitReasonSelectNoCases // "select (no cases)" |
| waitReasonGCAssistWait // "GC assist wait" |
| waitReasonGCSweepWait // "GC sweep wait" |
| waitReasonGCScavengeWait // "GC scavenge wait" |
| waitReasonChanReceive // "chan receive" |
| waitReasonChanSend // "chan send" |
| waitReasonFinalizerWait // "finalizer wait" |
| waitReasonForceGCIdle // "force gc (idle)" |
| waitReasonSemacquire // "semacquire" |
| waitReasonSleep // "sleep" |
| waitReasonSyncCondWait // "sync.Cond.Wait" |
| waitReasonTimerGoroutineIdle // "timer goroutine (idle)" |
| waitReasonTraceReaderBlocked // "trace reader (blocked)" |
| waitReasonWaitForGCCycle // "wait for GC cycle" |
| waitReasonGCWorkerIdle // "GC worker (idle)" |
| waitReasonPreempted // "preempted" |
| waitReasonDebugCall // "debug call" |
| ) |
| |
| var waitReasonStrings = [...]string{ |
| waitReasonZero: "", |
| waitReasonGCAssistMarking: "GC assist marking", |
| waitReasonIOWait: "IO wait", |
| waitReasonChanReceiveNilChan: "chan receive (nil chan)", |
| waitReasonChanSendNilChan: "chan send (nil chan)", |
| waitReasonDumpingHeap: "dumping heap", |
| waitReasonGarbageCollection: "garbage collection", |
| waitReasonGarbageCollectionScan: "garbage collection scan", |
| waitReasonPanicWait: "panicwait", |
| waitReasonSelect: "select", |
| waitReasonSelectNoCases: "select (no cases)", |
| waitReasonGCAssistWait: "GC assist wait", |
| waitReasonGCSweepWait: "GC sweep wait", |
| waitReasonGCScavengeWait: "GC scavenge wait", |
| waitReasonChanReceive: "chan receive", |
| waitReasonChanSend: "chan send", |
| waitReasonFinalizerWait: "finalizer wait", |
| waitReasonForceGCIdle: "force gc (idle)", |
| waitReasonSemacquire: "semacquire", |
| waitReasonSleep: "sleep", |
| waitReasonSyncCondWait: "sync.Cond.Wait", |
| waitReasonTimerGoroutineIdle: "timer goroutine (idle)", |
| waitReasonTraceReaderBlocked: "trace reader (blocked)", |
| waitReasonWaitForGCCycle: "wait for GC cycle", |
| waitReasonGCWorkerIdle: "GC worker (idle)", |
| waitReasonPreempted: "preempted", |
| waitReasonDebugCall: "debug call", |
| } |
| |
| func (w waitReason) String() string { |
| if w < 0 || w >= waitReason(len(waitReasonStrings)) { |
| return "unknown wait reason" |
| } |
| return waitReasonStrings[w] |
| } |
| |
| var ( |
| allm *m |
| gomaxprocs int32 |
| ncpu int32 |
| forcegc forcegcstate |
| sched schedt |
| newprocs int32 |
| |
| // allpLock protects P-less reads and size changes of allp, idlepMask, |
| // and timerpMask, and all writes to allp. |
| allpLock mutex |
| // len(allp) == gomaxprocs; may change at safe points, otherwise |
| // immutable. |
| allp []*p |
| // Bitmask of Ps in _Pidle list, one bit per P. Reads and writes must |
| // be atomic. Length may change at safe points. |
| // |
| // Each P must update only its own bit. In order to maintain |
| // consistency, a P going idle must the idle mask simultaneously with |
| // updates to the idle P list under the sched.lock, otherwise a racing |
| // pidleget may clear the mask before pidleput sets the mask, |
| // corrupting the bitmap. |
| // |
| // N.B., procresize takes ownership of all Ps in stopTheWorldWithSema. |
| idlepMask pMask |
| // Bitmask of Ps that may have a timer, one bit per P. Reads and writes |
| // must be atomic. Length may change at safe points. |
| timerpMask pMask |
| |
| // Pool of GC parked background workers. Entries are type |
| // *gcBgMarkWorkerNode. |
| gcBgMarkWorkerPool lfstack |
| |
| // Total number of gcBgMarkWorker goroutines. Protected by worldsema. |
| gcBgMarkWorkerCount int32 |
| |
| support_aes bool |
| ) |
| |
| // Set by the linker so the runtime can determine the buildmode. |
| var ( |
| islibrary bool // -buildmode=c-shared |
| isarchive bool // -buildmode=c-archive |
| ) |
| |
| // Types that are only used by gccgo. |
| |
| // g_ucontext_t is a Go version of the C ucontext_t type, used by getcontext. |
| // _sizeof_ucontext_t is defined by mkrsysinfo.sh from <ucontext.h>. |
| // On some systems getcontext and friends require a value that is |
| // aligned to a 16-byte boundary. We implement this by increasing the |
| // required size and picking an appropriate offset when we use the |
| // array. |
| type g_ucontext_t [(_sizeof_ucontext_t + 15) / unsafe.Sizeof(uintptr(0))]uintptr |
| |
| // sigset is the Go version of the C type sigset_t. |
| // _sigset_t is defined by the Makefile from <signal.h>. |
| type sigset _sigset_t |
| |
| // getMemstats returns a pointer to the internal memstats variable, |
| // for C code. |
| //go:linkname getMemstats |
| func getMemstats() *mstats { |
| return &memstats |
| } |