zrepl/client/pprof_listen.go
Christian Schwarz 10a14a8c50 [#307] add package trace, integrate it with logging, and adopt it throughout zrepl
package trace:

- introduce the concept of tasks and spans, tracked as linked list within ctx
    - see package-level docs for an overview of the concepts
    - **main feature 1**: unique stack of task and span IDs
        - makes it easy to follow a series of log entries in concurrent code
    - **main feature 2**: ability to produce a chrome://tracing-compatible trace file
        - either via an env variable or a `zrepl pprof` subcommand
        - this is not a CPU profile, we already have go pprof for that
        - but it is very useful to visually inspect where the
          replication / snapshotter / pruner spends its time
          ( fixes #307 )

usage in package daemon/logging:

- goal: every log entry should have a trace field with the ID stack from package trace

- make `logging.GetLogger(ctx, Subsys)` the authoritative `logger.Logger` factory function
    - the context carries a linked list of injected fields which
      `logging.GetLogger` adds to the logger it returns
    - `logging.GetLogger` also uses package `trace` to get the
      task-and-span-stack and injects it into the returned logger's fields
2020-05-19 11:30:02 +02:00

69 lines
1.5 KiB
Go

package client
import (
"context"
"errors"
"log"
"os"
"github.com/zrepl/zrepl/cli"
"github.com/zrepl/zrepl/config"
"github.com/zrepl/zrepl/daemon"
)
var pprofListenCmd struct {
daemon.PprofServerControlMsg
}
var PprofListenCmd = &cli.Subcommand{
Use: "listen off | [on TCP_LISTEN_ADDRESS]",
Short: "start a http server exposing go-tool-compatible profiling endpoints at TCP_LISTEN_ADDRESS",
Run: func(ctx context.Context, subcommand *cli.Subcommand, args []string) error {
if len(args) < 1 {
goto enargs
}
switch args[0] {
case "on":
pprofListenCmd.Run = true
if len(args) != 2 {
return errors.New("must specify TCP_LISTEN_ADDRESS as second positional argument")
}
pprofListenCmd.HttpListenAddress = args[1]
case "off":
if len(args) != 1 {
goto enargs
}
pprofListenCmd.Run = false
}
RunPProf(subcommand.Config())
return nil
enargs:
return errors.New("invalid number of positional arguments")
},
}
func RunPProf(conf *config.Config) {
log := log.New(os.Stderr, "", 0)
die := func() {
log.Printf("exiting after error")
os.Exit(1)
}
log.Printf("connecting to zrepl daemon")
httpc, err := controlHttpClient(conf.Global.Control.SockPath)
if err != nil {
log.Printf("error creating http client: %s", err)
die()
}
err = jsonRequestResponse(httpc, daemon.ControlJobEndpointPProf, pprofListenCmd.PprofServerControlMsg, struct{}{})
if err != nil {
log.Printf("error sending control message: %s", err)
die()
}
log.Printf("finished")
}