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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
56 lines
1.1 KiB
Go
56 lines
1.1 KiB
Go
package semaphore
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import (
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"context"
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"sync"
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"sync/atomic"
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"testing"
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"time"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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"github.com/zrepl/zrepl/daemon/logging/trace"
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)
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func TestSemaphore(t *testing.T) {
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const numGoroutines = 10
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const concurrentSemaphore = 5
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const sleepTime = 1 * time.Second
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begin := time.Now()
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sem := New(concurrentSemaphore)
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var acquisitions struct {
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beforeT, afterT uint32
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}
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ctx := context.Background()
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defer trace.WithTaskFromStackUpdateCtx(&ctx)()
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var wg sync.WaitGroup
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wg.Add(numGoroutines)
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for i := 0; i < numGoroutines; i++ {
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go func() {
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ctx, end := trace.WithTaskFromStack(ctx)
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defer end()
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defer wg.Done()
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res, err := sem.Acquire(ctx)
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require.NoError(t, err)
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defer res.Release()
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if time.Since(begin) > sleepTime {
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atomic.AddUint32(&acquisitions.beforeT, 1)
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} else {
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atomic.AddUint32(&acquisitions.afterT, 1)
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}
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time.Sleep(sleepTime)
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}()
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}
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wg.Wait()
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assert.True(t, acquisitions.beforeT == concurrentSemaphore)
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assert.True(t, acquisitions.afterT == numGoroutines-concurrentSemaphore)
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}
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