| commit | 5bba5b256ce287736da60372c5cf634395d7b1a3 | [log] [tgz] |
|---|---|---|
| author | Michael Anthony Knyszek <mknyszek@google.com> | Fri Mar 15 22:18:06 2024 +0000 |
| committer | Michael Knyszek <mknyszek@google.com> | Wed Apr 10 18:52:49 2024 +0000 |
| tree | 8bbb410d62048d6a5d472d2f37c8a17ddb14450e | |
| parent | 73981695a2518b6eae7f8ffe74d224691c60d433 [diff] |
runtime: rewrite traceMap to scale better The existing implementation of traceMap is a hash map with a fixed bucket table size which scales poorly with the number of elements added to the map. After a few thousands elements are in the map, it tends to fall over. Furthermore, cleaning up the trace map is currently non-preemptible, without very good reason. This change replaces the traceMap implementation with a simple append-only concurrent hash-trie. The data structure is incredibly simple and does not suffer at all from the same scaling issues. Because the traceMap no longer has a lock, and the traceRegionAlloc it embeds is not thread-safe, we have to push that lock down. While we're here, this change also makes the fast path for the traceRegionAlloc lock-free. This may not be inherently faster due to contention on the atomic add, but it creates an easy path to sharding the main allocation buffer to reduce contention in the future. (We might want to also consider a fully thread-local allocator that covers both string and stack tables. The only reason a thread-local allocator isn't feasible right now is because each of these has their own region, but we could certainly group all them together.) Change-Id: I8c06d42825c326061a1b8569e322afc4bc2a513a Reviewed-on: https://go-review.googlesource.com/c/go/+/570035 Reviewed-by: Carlos Amedee <carlos@golang.org> Auto-Submit: Michael Knyszek <mknyszek@google.com> TryBot-Bypass: Michael Knyszek <mknyszek@google.com> Reviewed-by: David Chase <drchase@google.com>
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