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https://github.com/zrepl/zrepl.git
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10a14a8c50
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
45 lines
949 B
Go
45 lines
949 B
Go
package client
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import (
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"context"
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"io"
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"log"
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"os"
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"golang.org/x/net/websocket"
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"github.com/zrepl/zrepl/cli"
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)
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var pprofActivityTraceCmd = &cli.Subcommand{
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Use: "activity-trace ZREPL_PPROF_HOST:ZREPL_PPROF_PORT",
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Short: "attach to zrepl daemon with activated pprof listener and dump an activity-trace to stdout",
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Run: runPProfActivityTrace,
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}
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func runPProfActivityTrace(ctx context.Context, subcommand *cli.Subcommand, args []string) error {
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log := log.New(os.Stderr, "", 0)
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die := func() {
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log.Printf("exiting after error")
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os.Exit(1)
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}
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if len(args) != 1 {
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log.Printf("exactly one positional argument is required")
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die()
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}
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url := "ws://" + args[0] + "/debug/zrepl/activity-trace" // FIXME dont' repeat that
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log.Printf("attaching to activity trace stream %s", url)
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ws, err := websocket.Dial(url, "", url)
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if err != nil {
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log.Printf("error: %s", err)
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die()
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}
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_, err = io.Copy(os.Stdout, ws)
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return err
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}
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