From bd296e799bd3eceaa3c3f3db1227f9dba62bb1a1 Mon Sep 17 00:00:00 2001
From: Michael Pratt <mpratt@google.com>
Date: Mon, 13 Sep 2021 18:07:29 -0400
Subject: runsc: add global profile collection flags

Add global flags -profile-{block,cpu,heap,mutex} and -trace which
enable collection of the specified profile for the entire duration of a
container execution. This provides a way to definitively start profiling
before that application starts, rather than attempting to race with an
out-of-band `runsc debug`.

Note that only the main boot process is profiled.

This exposed a bug in Task.traceExecEvent: a crash when tracing and
-race are enabled. traceExecEvent is called off of the task goroutine,
but uses the Task as a context, which is a violation of the Task
contract. Switching to the AsyncContext fixes the issue.

Fixes #220
---
 runsc/boot/loader.go | 36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

(limited to 'runsc/boot/loader.go')

diff --git a/runsc/boot/loader.go b/runsc/boot/loader.go
index 1dd0048ac..b46d84e5a 100644
--- a/runsc/boot/loader.go
+++ b/runsc/boot/loader.go
@@ -120,6 +120,10 @@ type Loader struct {
 	// container. It should be called when a sandbox is destroyed.
 	stopSignalForwarding func()
 
+	// stopProfiling stops profiling started at container creation. It
+	// should be called when a sandbox is destroyed.
+	stopProfiling func()
+
 	// restore is set to true if we are restoring a container.
 	restore bool
 
@@ -199,6 +203,21 @@ type Args struct {
 	TotalMem uint64
 	// UserLogFD is the file descriptor to write user logs to.
 	UserLogFD int
+	// ProfileBlockFD is the file descriptor to write a block profile to.
+	// Valid if >=0.
+	ProfileBlockFD int
+	// ProfileCPUFD is the file descriptor to write a CPU profile to.
+	// Valid if >=0.
+	ProfileCPUFD int
+	// ProfileHeapFD is the file descriptor to write a heap profile to.
+	// Valid if >=0.
+	ProfileHeapFD int
+	// ProfileMutexFD is the file descriptor to write a mutex profile to.
+	// Valid if >=0.
+	ProfileMutexFD int
+	// TraceFD is the file descriptor to write a Go execution trace to.
+	// Valid if >=0.
+	TraceFD int
 }
 
 // make sure stdioFDs are always the same on initial start and on restore
@@ -207,6 +226,8 @@ const startingStdioFD = 256
 // New initializes a new kernel loader configured by spec.
 // New also handles setting up a kernel for restoring a container.
 func New(args Args) (*Loader, error) {
+	stopProfiling := startProfiling(args)
+
 	// We initialize the rand package now to make sure /dev/urandom is pre-opened
 	// on kernels that do not support getrandom(2).
 	if err := rand.Init(); err != nil {
@@ -400,12 +421,13 @@ func New(args Args) (*Loader, error) {
 
 	eid := execID{cid: args.ID}
 	l := &Loader{
-		k:          k,
-		watchdog:   dog,
-		sandboxID:  args.ID,
-		processes:  map[execID]*execProcess{eid: {}},
-		mountHints: mountHints,
-		root:       info,
+		k:             k,
+		watchdog:      dog,
+		sandboxID:     args.ID,
+		processes:     map[execID]*execProcess{eid: {}},
+		mountHints:    mountHints,
+		root:          info,
+		stopProfiling: stopProfiling,
 	}
 
 	// We don't care about child signals; some platforms can generate a
@@ -498,6 +520,8 @@ func (l *Loader) Destroy() {
 	for _, f := range l.root.goferFDs {
 		_ = f.Close()
 	}
+
+	l.stopProfiling()
 }
 
 func createPlatform(conf *config.Config, deviceFile *os.File) (platform.Platform, error) {
-- 
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