• Dmitry Vyukov's avatar
    runtime: fix finalization and profiling of tiny allocations · bf606094
    Dmitry Vyukov authored
    Handling of special records for tiny allocations has two problems:
    1. Once we queue a finalizer we mark the object. As the result any
       subsequent finalizers for the same object will not be queued
       during this GC cycle. If we have 16 finalizers setup (the worst case),
       finalization will take 16 GC cycles. This is what caused misbehave
       of tinyfin.go. The actual flakiness was caused by the fact that fing
       is asynchronous and don't always run before the check.
    2. If a tiny block has both finalizer and profile specials,
       it is possible that we both queue finalizer, preserve the object live
       and free the profile record. As the result heap profile can be skewed.
    
    Fix both issues by analyzing all special records for a single object at once.
    
    Also, make tinyfin test stricter and remove reliance on real time.
    
    Also, add a test for the problem 2. Currently heap profile missed about
    a half of live memory.
    
    Fixes #13100
    
    Change-Id: I9ae4dc1c44893724138a4565ca5cae29f2e97544
    Reviewed-on: https://go-review.googlesource.com/16591Reviewed-by: 's avatarAustin Clements <austin@google.com>
    Reviewed-by: 's avatarKeith Randall <khr@golang.org>
    Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
    bf606094
finprofiled.go 1.94 KB