commit | 91c385b3936e757e4cda01c9265de3b4abf601c3 | [log] [tgz] |
---|---|---|
author | Russ Cox <rsc@golang.org> | Fri Jun 28 01:42:08 2019 -0400 |
committer | Russ Cox <rsc@golang.org> | Fri Jun 28 20:09:48 2019 +0000 |
tree | be4eda2d59f107bd0a548fa63ce748a63c7f5cd3 | |
parent | 3b040b7e8088ad2c02e413a4abf7effcd62373d0 [diff] |
runtime: fix pprof cpu profile corruption on arm/mips/mipsle CL 42652 changed the profile handler for mips/mipsle to avoid recording a profile when in atomic functions, for fear of interrupting the 32-bit simulation of a 64-bit atomic with a lock. The profile logger itself uses 64-bit atomics and might deadlock (#20146). The change was to accumulate a count of dropped profile events and then send the count when the next ordinary event was sent: if prof.hz != 0 { + if (GOARCH == "mips" || GOARCH == "mipsle") && lostAtomic64Count > 0 { + cpuprof.addLostAtomic64(lostAtomic64Count) + lostAtomic64Count = 0 + } cpuprof.add(gp, stk[:n]) } CL 117057 extended this behavior to include GOARCH == "arm". Unfortunately, the inserted cpuprof.addLostAtomic64 differs from the original cpuprof.add in that it neglects to acquire the lock protecting the profile buffer. This has caused a steady stream of flakes on the arm builders for the past 12 months, ever since CL 117057 landed. This CL moves the lostAtomic count into the profile buffer and then lets the existing addExtra calls take care of it, instead of duplicating the locking logic. Fixes #24991. Change-Id: Ia386c40034fcf46b31f080ce18f2420df4bb8004 Reviewed-on: https://go-review.googlesource.com/c/go/+/184164 Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Cherry Zhang <cherryyz@google.com>
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