models/db/error.go

@@ -5,6 +5,7 @@ package db
 
 import (
 	"fmt"
+	"strings"
 
 	"git.mokoconsulting.tech/MokoConsulting/MokoGitea/modules/util"
 )
@@ -72,3 +73,27 @@ func (err ErrNotExist) Error() string {
 func (err ErrNotExist) Unwrap() error {
 	return util.ErrNotExist
 }
+
+// IsErrDeadlock checks whether err is a database deadlock.
+// MySQL returns error 1213 (ER_LOCK_DEADLOCK / SQLSTATE 40001).
+// PostgreSQL returns SQLSTATE 40P01 with "deadlock detected".
+// SQLite returns SQLITE_BUSY (error 5) with "database is locked".
+func IsErrDeadlock(err error) bool {
+	if err == nil {
+		return false
+	}
+	msg := err.Error()
+	// MySQL / MariaDB: "Error 1213 (40001): Deadlock found when trying to get lock"
+	if strings.Contains(msg, "Error 1213") || strings.Contains(msg, "40001") {
+		return true
+	}
+	// PostgreSQL: "deadlock detected"
+	if strings.Contains(msg, "deadlock detected") {
+		return true
+	}
+	// SQLite: "database is locked"
+	if strings.Contains(msg, "database is locked") {
+		return true
+	}
+	return false
+}

models/db/error_test.go

@@ -0,0 +1,31 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIsErrDeadlock(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{name: "nil", err: nil, want: false},
+		{name: "unrelated", err: errors.New("connection refused"), want: false},
+		{name: "mysql 1213", err: errors.New("Error 1213 (40001): Deadlock found when trying to get lock; try restarting transaction"), want: true},
+		{name: "mysql sqlstate", err: errors.New("SQLSTATE 40001: serialization failure"), want: true},
+		{name: "postgres", err: errors.New("pq: deadlock detected"), want: true},
+		{name: "sqlite", err: errors.New("database is locked"), want: true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, IsErrDeadlock(tt.err))
+		})
+	}
+}

services/actions/notifier_helper.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"slices"
 	"strings"
+	"time"
 
 	actions_model "git.mokoconsulting.tech/MokoConsulting/MokoGitea/models/actions"
 	"git.mokoconsulting.tech/MokoConsulting/MokoGitea/models/db"
@@ -344,7 +345,7 @@ func handleWorkflows(
 
 		run.NeedApproval = need
 
-		if err := PrepareRunAndInsert(ctx, dwf.Content, run, nil); err != nil {
+		if err := prepareRunAndInsertWithRetry(ctx, dwf.Content, run); err != nil {
 			log.Error("PrepareRunAndInsert: %v", err)
 			continue
 		}
@@ -352,6 +353,54 @@ func handleWorkflows(
 	return nil
 }
 
+// prepareRunAndInsertWithRetry wraps PrepareRunAndInsert with retries on
+// database deadlocks.  When multiple workflow runs are inserted for the same
+// event (e.g. several workflows triggered by a single pull_request), each
+// InsertRun transaction acquires an X-lock on the repository row (via
+// UpdateRepoRunsNumbers) and an index lock on action_run.  Two concurrent
+// transactions can deadlock when each holds one lock and waits for the other.
+// InnoDB resolves this by killing the lighter transaction, but handleWorkflows
+// only logged the error and moved on — silently dropping the workflow run.
+// Retrying the insert is safe because the rolled-back transaction left no
+// partial state.
+func prepareRunAndInsertWithRetry(ctx context.Context, content []byte, run *actions_model.ActionRun) error {
+	const maxRetries = 3
+	backoff := 50 * time.Millisecond
+
+	// Save original values that InsertRun mutates inside its transaction.
+	// On deadlock rollback these become stale and must be reset before retry.
+	origTitle := run.Title
+
+	var err error
+	for attempt := range maxRetries {
+		if err = PrepareRunAndInsert(ctx, content, run, nil); err == nil {
+			return nil
+		}
+		if !db.IsErrDeadlock(err) {
+			return err
+		}
+		log.Warn("PrepareRunAndInsert deadlock (attempt %d/%d) for workflow %s in repo %d, retrying: %v",
+			attempt+1, maxRetries, run.WorkflowID, run.RepoID, err)
+
+		// Reset fields that InsertRun sets inside the (now rolled-back) transaction
+		// so the next attempt starts clean.
+		run.ID = 0
+		run.Index = 0
+		run.Status = actions_model.StatusWaiting
+		run.Title = origTitle
+		run.ConcurrencyGroup = ""
+		run.ConcurrencyCancel = false
+
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case <-time.After(backoff):
+		}
+		backoff *= 2
+	}
+	return fmt.Errorf("deadlock persisted after %d retries: %w", maxRetries, err)
+}
+
 func newNotifyInputFromIssue(issue *issues_model.Issue, event webhook_module.HookEventType) *notifyInput {
 	return newNotifyInput(issue.Repo, issue.Poster, event)
 }