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193abbe6b1
The goroutine that does endTask() for
"list-abstractions-streamed-producer" can be preempted
after it has closed the out and outErrs channel,
but before it calls endTask().
If the parent ("handler") then gets scheduled and
and ends itself, it will observe an active child task
"list-abstractions-streamed-producer".
This is easy to demo by injecting a sleep here:
--- a/endpoint/endpoint_zfs_abstraction.go
+++ b/endpoint/endpoint_zfs_abstraction.go
@@ -575,6 +576,7 @@ func ListAbstractionsStreamed(ctx context.Context, query ListZFSHoldsAndBookmark
ctx, endTask := trace.WithTask(ctx, "list-abstractions-streamed-producer")
go func() {
defer endTask()
+ defer time.Sleep(10 * time.Second)
defer close(out)
defer close(outErrs)
fixes https://github.com/zrepl/zrepl/issues/607
101 lines
2.1 KiB
Go
101 lines
2.1 KiB
Go
package client
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import (
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"context"
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"encoding/json"
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"fmt"
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"os"
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"sync"
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"github.com/fatih/color"
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"github.com/pkg/errors"
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"github.com/spf13/pflag"
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"github.com/zrepl/zrepl/cli"
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"github.com/zrepl/zrepl/endpoint"
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"github.com/zrepl/zrepl/util/chainlock"
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)
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var zabsListFlags struct {
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Filter zabsFilterFlags
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Json bool
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}
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var zabsCmdList = &cli.Subcommand{
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Use: "list",
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Short: `list zrepl ZFS abstractions`,
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Run: doZabsList,
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NoRequireConfig: true,
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SetupFlags: func(f *pflag.FlagSet) {
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zabsListFlags.Filter.registerZabsFilterFlags(f, "list")
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f.BoolVar(&zabsListFlags.Json, "json", false, "emit JSON")
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},
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}
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func doZabsList(ctx context.Context, sc *cli.Subcommand, args []string) error {
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var err error
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if len(args) > 0 {
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return errors.New("this subcommand takes no positional arguments")
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}
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q, err := zabsListFlags.Filter.Query()
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if err != nil {
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return errors.Wrap(err, "invalid filter specification on command line")
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}
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abstractions, errors, drainDone, err := endpoint.ListAbstractionsStreamed(ctx, q)
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if err != nil {
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return err // context clear by invocation of command
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}
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defer drainDone()
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var line chainlock.L
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var wg sync.WaitGroup
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defer wg.Wait()
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// print results
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wg.Add(1)
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go func() {
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defer wg.Done()
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enc := json.NewEncoder(os.Stdout)
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for a := range abstractions {
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func() {
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defer line.Lock().Unlock()
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if zabsListFlags.Json {
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enc.SetIndent("", " ")
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if err := enc.Encode(a); err != nil {
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panic(err)
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}
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fmt.Println()
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} else {
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fmt.Println(a)
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}
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}()
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}
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}()
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// print errors to stderr
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errorColor := color.New(color.FgRed)
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var errorsSlice []endpoint.ListAbstractionsError
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wg.Add(1)
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go func() {
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defer wg.Done()
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for err := range errors {
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func() {
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defer line.Lock().Unlock()
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errorsSlice = append(errorsSlice, err)
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errorColor.Fprintf(os.Stderr, "%s\n", err)
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}()
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}
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}()
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wg.Wait()
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if len(errorsSlice) > 0 {
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errorColor.Add(color.Bold).Fprintf(os.Stderr, "there were errors in listing the abstractions")
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return fmt.Errorf("")
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} else {
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return nil
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}
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}
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