Add profiling commands to runsc

Example:
  runsc debug --root=<dir> \
      --profile-heap=/tmp/heap.prof \
      --profile-cpu=/tmp/cpu.prod --profile-delay=30 \
      <container ID>
PiperOrigin-RevId: 237848456
Change-Id: Icff3f20c1b157a84d0922599eaea327320dad773

2 files changed, 126 insertions, 0 deletions

diff --git a/pkg/sentry/control/BUILD b/pkg/sentry/control/BUILD
index f54e01ee8..5052bcc0d 100644
--- a/pkg/sentry/control/BUILD
+++ b/pkg/sentry/control/BUILD
@@ -6,6 +6,7 @@ go_library(
     name = "control",
     srcs = [
         "control.go",
+        "pprof.go",
         "proc.go",
         "state.go",
     ],
@@ -15,6 +16,7 @@ go_library(
     ],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/fd",
         "//pkg/log",
         "//pkg/sentry/fs",
         "//pkg/sentry/fs/host",
diff --git a/pkg/sentry/control/pprof.go b/pkg/sentry/control/pprof.go
new file mode 100644
index 000000000..1af092af3
--- /dev/null
+++ b/pkg/sentry/control/pprof.go
@@ -0,0 +1,124 @@
+// Copyright 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package control
+
+import (
+	"errors"
+	"runtime"
+	"runtime/pprof"
+	"sync"
+
+	"gvisor.googlesource.com/gvisor/pkg/fd"
+	"gvisor.googlesource.com/gvisor/pkg/urpc"
+)
+
+var errNoOutput = errors.New("no output writer provided")
+
+// ProfileOpts contains options for the StartCPUProfile/Goroutine RPC call.
+type ProfileOpts struct {
+	// File is the filesystem path for the profile.
+	File string `json:"path"`
+
+	// FilePayload is the destination for the profiling output.
+	urpc.FilePayload
+}
+
+// Profile includes profile-related RPC stubs. It provides a way to
+// control the built-in pprof facility in sentry via sentryctl.
+//
+// The following options to sentryctl are added:
+//
+// - collect CPU profile on-demand.
+//   sentryctl -pid <pid> pprof-cpu-start
+//   sentryctl -pid <pid> pprof-cpu-stop
+//
+// - dump out the stack trace of current go routines.
+//   sentryctl -pid <pid> pprof-goroutine
+type Profile struct {
+	// mu protects the fields below.
+	mu sync.Mutex
+
+	// cpuFile is the current CPU profile output file.
+	cpuFile *fd.FD
+}
+
+// StartCPUProfile is an RPC stub which starts recording the CPU profile in a
+// file.
+func (p *Profile) StartCPUProfile(o *ProfileOpts, _ *struct{}) error {
+	if len(o.FilePayload.Files) < 1 {
+		return errNoOutput
+	}
+
+	output, err := fd.NewFromFile(o.FilePayload.Files[0])
+	if err != nil {
+		return err
+	}
+
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	// Returns an error if profiling is already started.
+	if err := pprof.StartCPUProfile(output); err != nil {
+		output.Close()
+		return err
+	}
+
+	p.cpuFile = output
+	return nil
+}
+
+// StopCPUProfile is an RPC stub which stops the CPU profiling and flush out the
+// profile data. It takes no argument.
+func (p *Profile) StopCPUProfile(_, _ *struct{}) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	if p.cpuFile == nil {
+		return errors.New("CPU profiling not started")
+	}
+
+	pprof.StopCPUProfile()
+	p.cpuFile.Close()
+	p.cpuFile = nil
+	return nil
+}
+
+// HeapProfile generates a heap profile for the sentry.
+func (p *Profile) HeapProfile(o *ProfileOpts, _ *struct{}) error {
+	if len(o.FilePayload.Files) < 1 {
+		return errNoOutput
+	}
+	output := o.FilePayload.Files[0]
+	defer output.Close()
+	runtime.GC() // Get up-to-date statistics.
+	if err := pprof.WriteHeapProfile(output); err != nil {
+		return err
+	}
+	return nil
+}
+
+// Goroutine is an RPC stub which dumps out the stack trace for all running
+// goroutines.
+func (p *Profile) Goroutine(o *ProfileOpts, _ *struct{}) error {
+	if len(o.FilePayload.Files) < 1 {
+		return errNoOutput
+	}
+	output := o.FilePayload.Files[0]
+	defer output.Close()
+	if err := pprof.Lookup("goroutine").WriteTo(output, 2); err != nil {
+		return err
+	}
+	return nil
+}