runtime: clean up redundant calls to SetGCPercent in debug_test.go

SetGCPercent(-1) is called by several tests in debug_test.go (followed
by a call to runtime.GC) due to #49370. However, startDebugCallWorker
already actually has this, just without the runtime.GC call (allowing an
in-progress GC to still mess up the test).

This CL consolidates SetGCPercent into startDebugDebugCallWorker where
applicable.

Change-Id: Ifa12d6a911f1506e252d3ddf03004cf2ab3f4ee4
Reviewed-on: https://go-review.googlesource.com/c/go/+/369751
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

diff --git a/src/runtime/debug_test.go b/src/runtime/debug_test.go
index 89ea577d644d91811bccdadb6c3feb4e79a69d3b..44585b1744af991cd304fbbcc08bbd916bc42c52 100644 (file)
--- a/src/runtime/debug_test.go
+++ b/src/runtime/debug_test.go
@@ -34,12 +34,15 @@ func startDebugCallWorker(t *testing.T) (g *runtime.G, after func()) {
        skipUnderDebugger(t)
 
        // This can deadlock if there aren't enough threads or if a GC
-       // tries to interrupt an atomic loop (see issue #10958). We
+       // tries to interrupt an atomic loop (see issue #10958). A GC
+       // could also actively be in progress (see issue #49370), so we
+       // need to call runtime.GC to block until it has complete. We
        // use 8 Ps so there's room for the debug call worker,
        // something that's trying to preempt the call worker, and the
        // goroutine that's trying to stop the call worker.
        ogomaxprocs := runtime.GOMAXPROCS(8)
        ogcpercent := debug.SetGCPercent(-1)
+       runtime.GC()
 
        // ready is a buffered channel so debugCallWorker won't block
        // on sending to it. This makes it less likely we'll catch
@@ -114,13 +117,6 @@ func skipUnderDebugger(t *testing.T) {
 }
 
 func TestDebugCall(t *testing.T) {
-       // InjectDebugCall cannot be executed while a GC is actively in
-       // progress. Wait until the current GC is done, and turn it off.
-       //
-       // See #49370.
-       runtime.GC()
-       defer debug.SetGCPercent(debug.SetGCPercent(-1))
-
        g, after := startDebugCallWorker(t)
        defer after()
 
@@ -172,13 +168,6 @@ func TestDebugCall(t *testing.T) {
 }
 
 func TestDebugCallLarge(t *testing.T) {
-       // InjectDebugCall cannot be executed while a GC is actively in
-       // progress. Wait until the current GC is done, and turn it off.
-       //
-       // See #49370.
-       runtime.GC()
-       defer debug.SetGCPercent(debug.SetGCPercent(-1))
-
        g, after := startDebugCallWorker(t)
        defer after()
 
@@ -208,13 +197,6 @@ func TestDebugCallLarge(t *testing.T) {
 }
 
 func TestDebugCallGC(t *testing.T) {
-       // InjectDebugCall cannot be executed while a GC is actively in
-       // progress. Wait until the current GC is done, and turn it off.
-       //
-       // See #49370.
-       runtime.GC()
-       defer debug.SetGCPercent(debug.SetGCPercent(-1))
-
        g, after := startDebugCallWorker(t)
        defer after()
 
@@ -225,13 +207,6 @@ func TestDebugCallGC(t *testing.T) {
 }
 
 func TestDebugCallGrowStack(t *testing.T) {
-       // InjectDebugCall cannot be executed while a GC is actively in
-       // progress. Wait until the current GC is done, and turn it off.
-       //
-       // See #49370.
-       runtime.GC()
-       defer debug.SetGCPercent(debug.SetGCPercent(-1))
-
        g, after := startDebugCallWorker(t)
        defer after()
 
@@ -294,7 +269,7 @@ func TestDebugCallPanic(t *testing.T) {
        // InjectDebugCall cannot be executed while a GC is actively in
        // progress. Wait until the current GC is done, and turn it off.
        //
-       // See #49370.
+       // See #10958 and #49370.
        runtime.GC()
        defer debug.SetGCPercent(debug.SetGCPercent(-1))