1. 17 Dec, 2018 1 commit
    • Austin Clements's avatar
      runtime: fix hangs in TestDebugCall* · a27f3d5c
      Austin Clements authored
      This fixes a few different issues that led to hangs and general
      flakiness in the TestDebugCall* tests.
      
      1. This fixes missing wake-ups in two error paths of the SIGTRAP
         signal handler. If the goroutine was in an unknown state, or if
         there was an unknown debug call status, we currently don't wake the
         injection coordinator. These are terminal states, so this resulted
         in a hang.
      
      2. This adds a retry if the target goroutine is in a transient state
         that prevents us from injecting a call. The most common failure
         mode here is that the target goroutine is in _Grunnable, but this
         was previously masked because it deadlocked the test.
      
      3. Related to 2, this switches the "ready" signal from the target
         goroutine from a blocking channel send to a non-blocking channel
         send. This makes it much less likely that we'll catch this
         goroutine while it's in the runtime performing that send.
      
      4. This increases GOMAXPROCS from 2 to 8 during these tests. With the
         current setting of 2, we can have at most the non-preemptible
         goroutine we're injecting a call in to and the goroutine that's
         trying to make it exit. If anything else comes along, it can
         deadlock. One particular case I observed was in TestDebugCallGC,
         where runtime.GC() returns before the forEachP that prepares
         sweeping on all goroutines has finished. When this happens, the
         forEachP blocks on the non-preemptible loop, which means we now
         have at least three goroutines that need to run.
      
      Fixes #25519.
      
      Updates #29124.
      
      Change-Id: I7bc41dc0b865b7d0bb379cb654f9a1218bc37428
      Reviewed-on: https://go-review.googlesource.com/c/154112
      Run-TryBot: Austin Clements <austin@google.com>
      Reviewed-by: default avatarMichael Knyszek <mknyszek@google.com>
      a27f3d5c
  2. 16 Dec, 2018 1 commit
  3. 15 Dec, 2018 4 commits
  4. 14 Dec, 2018 15 commits
  5. 13 Dec, 2018 19 commits