Add some goroutine labels & dump stacks if we think we've hung

src/core/state.go

@@ -1,6 +1,7 @@
 package core
 
 import (
+	"bytes"
 	"crypto/sha1"
 	"crypto/sha256"
 	"fmt"
@@ -11,6 +12,7 @@ import (
 	iofs "io/fs"
 	"iter"
 	"path/filepath"
+	"runtime/pprof"
 	"sort"
 	"strings"
 	"sync"
@@ -630,6 +632,10 @@ func (state *BuildState) forwardResults() {
 		}
 	}()
 	activeTargets := map[*BuildTarget]struct{}{}
+	go func() {
+		time.Sleep(4 * time.Second)
+		dumpGoroutineInfo()
+	}()
 	// Persist this one timer throughout so we don't generate bazillions of them.
 	t := time.NewTimer(cycleCheckDuration)
 	t.Stop()
@@ -645,6 +651,7 @@ func (state *BuildState) forwardResults() {
 				}
 			case <-t.C:
 				go state.checkForCycles()
+				go dumpGoroutineInfo()
 				// Still need to get a result!
 				result = <-state.progress.internalResults
 			}
@@ -1534,3 +1541,10 @@ func (s BuildResultStatus) IsFailure() bool {
 func (s BuildResultStatus) IsActive() bool {
 	return s == PackageParsing || s == TargetBuilding || s == TargetTesting
 }
+
+// dumpGoroutineInfo logs out the goroutine stacks when we believe we might have hung.
+func dumpGoroutineInfo() {
+	var buf bytes.Buffer
+	pprof.Lookup("goroutine").WriteTo(&buf, 1)
+	log.Debug("Current stacks: %s", buf.String())
+}

src/parse/asp/interpreter.go

@@ -1,11 +1,13 @@
 package asp
 
 import (
+	"context"
 	"fmt"
 	"iter"
 	"path/filepath"
 	"reflect"
 	"runtime/debug"
+	"runtime/pprof"
 	"strings"
 	"sync"
 
@@ -206,6 +208,8 @@ func (i *interpreter) interpretStatements(s *scope, statements []*Statement) (re
 func (i *interpreter) Subinclude(pkgScope *scope, path string, label core.BuildLabel, preload bool) pyDict {
 	key := filepath.Join(path, pkgScope.state.CurrentSubrepo)
 	globals, err := i.subincludes.GetOrSet(key, func() (pyDict, error) {
+		pprof.SetGoroutineLabels(pprof.WithLabels(context.Background(), pprof.Labels("subinclude", path)))
+		defer pprof.SetGoroutineLabels(context.Background())
 		stmts, err := i.parseSubinclude(path)
 		if err != nil {
 			return nil, err

src/parse/parse_step.go

@@ -6,10 +6,12 @@
 package parse
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	iofs "io/fs"
 	"path/filepath"
+	"runtime/pprof"
 	"strings"
 
 	"github.com/thought-machine/please/src/cli/logging"
@@ -79,7 +81,9 @@ func parse(state *core.BuildState, label, dependent core.BuildLabel, mode core.P
 	if label.Subrepo != "" && label.PackageName == "" && label.Name == "" {
 		return nil
 	}
-	pkg, err = parsePackage(state, label, dependent, subrepo, mode)
+	pprof.Do(context.Background(), pprof.Labels("parse", label.String()), func(_ context.Context) {
+		pkg, err = parsePackage(state, label, dependent, subrepo, mode)
+	})
 
 	if err != nil {
 		return err