Files
mgmt/util/pprof/pprof.go
James Shubin d30ff6cfae legal: Remove year
Instead of constantly making these updates, let's just remove the year
since things are stored in git anyways, and this is not an actual modern
legal risk anymore.
2025-01-26 16:24:51 -05:00

96 lines
3.3 KiB
Go

// Mgmt
// Copyright (C) James Shubin and the project contributors
// Written by James Shubin <james@shubin.ca> and the project contributors
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
//
// Additional permission under GNU GPL version 3 section 7
//
// If you modify this program, or any covered work, by linking or combining it
// with embedded mcl code and modules (and that the embedded mcl code and
// modules which link with this program, contain a copy of their source code in
// the authoritative form) containing parts covered by the terms of any other
// license, the licensors of this program grant you additional permission to
// convey the resulting work. Furthermore, the licensors of this program grant
// the original author, James Shubin, additional permission to update this
// additional permission if he deems it necessary to achieve the goals of this
// additional permission.
// Package pprof is a simple wrapper around the pprof utility code which we use.
package pprof
import (
"context"
"fmt"
"log"
"os"
"os/signal"
"runtime/pprof"
"strings"
"syscall"
)
// Run looks in a special environment var for the path to log pprof data to and
// if it finds it, it begins profiling. If it doesn't find a special environment
// var, it returns nil. If this is not able to start logging, then it errors. If
// it starts logging, this waits for an exit signal in a goroutine and returns
// nil. The magic env name is MGMT_PPROF_PATH. Example usage:
// MGMT_PPROF_PATH="~/pprof/out.pprof" ./mgmt run lang examples/lang/hello.mcl
// go tool pprof -no_browser -http :10000 ~/pprof/out.pprof
func Run(ctx context.Context) error {
s := os.Getenv("MGMT_PPROF_PATH")
logf := func(format string, v ...interface{}) {
// TODO: is this a sane prefix to use here?
log.Printf(format, v...) // XXX: use parent logger when available
}
if s == "" || !strings.HasPrefix(s, "/") {
return nil // not activated
}
logf("pprof logging to: %s", s)
f, err := os.Create(s)
if err != nil {
return fmt.Errorf("could not create CPU profile: %v", err)
}
if err := pprof.StartCPUProfile(f); err != nil {
return fmt.Errorf("could not start CPU profile: %v", err)
}
signals := make(chan os.Signal, 1+1) // 1 * ^C + 1 * SIGTERM
signal.Notify(signals, os.Interrupt) // catch ^C
//signal.Notify(signals, os.Kill) // catch signals
signal.Notify(signals, syscall.SIGTERM)
go func() {
defer func() {
if err := f.Close(); err != nil {
logf("pprof write error: %v", err)
return
}
logf("pprof wrote file to: %s", s)
}()
defer pprof.StopCPUProfile()
select {
case sig := <-signals: // any signal will do
logf("pprof logging shutdown by sig: %v", sig)
case <-ctx.Done():
logf("pprof logging shutdown by ctx: %v", ctx.Err())
}
}()
return nil
}