Files
act_runner/internal/app/run/runner.go
Bo-Yi Wu f2d545565f perf: reduce runner-to-server connection load with adaptive reporting and polling (#819)
## Summary

Many teams self-host Gitea + Act Runner at scale. The current runner design causes excessive HTTP requests to the Gitea server, leading to high server load. This PR addresses three root causes: aggressive fixed-interval polling, per-task status reporting every 1 second regardless of activity, and unoptimized HTTP client configuration.

## Problem

The original architecture has these issues:

**1. Fixed 1-second reporting interval (RunDaemon)**

- Every running task calls ReportLog + ReportState every 1 second (2 HTTP requests/sec/task)
- These requests are sent even when there are no new log rows or state changes
- With 200 runners × 3 tasks each = **1,200 req/sec just for status reporting**

**2. Fixed 2-second polling interval (no backoff)**

- Idle runners poll FetchTask every 2 seconds forever, even when no jobs are queued
- No exponential backoff or jitter — all runners can synchronize after network recovery (thundering herd)
- 200 idle runners = **100 req/sec doing nothing useful**

**3. HTTP client not tuned**

- Uses http.DefaultClient with MaxIdleConnsPerHost=2, causing frequent TCP/TLS reconnects
- Creates two separate http.Client instances (one for Ping, one for Runner service) instead of sharing

**Total: ~1,300 req/sec for 200 runners with 3 tasks each**

## Solution

### Adaptive Event-Driven Log Reporting

Replace the recursive `time.AfterFunc(1s)` pattern in RunDaemon with a goroutine-based select event loop using three trigger mechanisms:

| Trigger | Default | Purpose |
|---------|---------|---------|
| `log_report_max_latency` | 3s | Guarantee even a single log line is delivered within this time |
| `log_report_interval` | 5s | Periodic sweep — steady-state cadence |
| `log_report_batch_size` | 100 rows | Immediate flush during bursty output (e.g., npm install) |

**Key design**: `log_report_max_latency` (3s) must be less than `log_report_interval` (5s) so the max-latency timer fires before the periodic ticker for single-line scenarios.

State reporting is decoupled to its own `state_report_interval` (default 5s), with immediate flush on step transitions (start/stop) via a stateNotify channel for responsive frontend UX.

Additionally:
- Skip ReportLog when `len(rows) == 0` (no pending log rows)
- Skip ReportState when `stateChanged == false && len(outputs) == 0` (nothing changed)
- Move expensive `proto.Clone` after the early-return check to avoid deep copies on no-op paths

### Polling Backoff with Jitter

Replace fixed `rate.Limiter` with adaptive exponential backoff:
- Track `consecutiveEmpty` and `consecutiveErrors` counters
- Interval doubles with each empty/error response: `base × 2^(n-1)`, capped at `fetch_interval_max` (default 60s)
- Add ±20% random jitter to prevent thundering herd
- Fetch first, sleep after ��� preserves burst=1 behavior for immediate first fetch on startup and after task completion

### HTTP Client Tuning

- Configure custom `http.Transport` with `MaxIdleConnsPerHost=10` (was 2)
- Share a single `http.Client` between PingService and RunnerService
- Add `IdleConnTimeout=90s` for clean connection lifecycle

## Load Reduction

For 200 runners × 3 tasks (70% with active log output):

| Component | Before | After | Reduction |
|-----------|--------|-------|-----------|
| Polling (idle) | 100 req/s | ~3.4 req/s | 97% |
| Log reporting | 420 req/s | ~84 req/s | 80% |
| State reporting | 126 req/s | ~25 req/s | 80% |
| **Total** | **~1,300 req/s** | **~113 req/s** | **~91%** |

## Frontend UX Impact

| Scenario | Before | After | Notes |
|----------|--------|-------|-------|
| Continuous output (npm install) | ~1s | ~5s | Periodic ticker sweep |
| Single line then silence | ~1s | ≤3s | maxLatencyTimer guarantee |
| Bursty output (100+ lines) | ~1s | <1s | Batch size immediate flush |
| Step start/stop | ~1s | <1s | stateNotify immediate flush |
| Job completion | ~1s | ~1s | Close() retry unchanged |

## New Configuration Options

All have safe defaults — existing config files need no changes:

```yaml
runner:
  fetch_interval_max: 60s        # Max backoff interval when idle
  log_report_interval: 5s        # Periodic log flush interval
  log_report_max_latency: 3s     # Max time a log row waits (must be < log_report_interval)
  log_report_batch_size: 100     # Immediate flush threshold
  state_report_interval: 5s      # State flush interval (step transitions are always immediate)
```

Config validation warns on invalid combinations:
- `fetch_interval_max < fetch_interval` → auto-corrected
- `log_report_max_latency >= log_report_interval` → warning (timer would be redundant)

## Test Plan

- [x] `go build ./...` passes
- [x] `go test ./...` passes (all existing + 3 new tests)
- [x] `golangci-lint run` — 0 issues
- [x] TestReporter_MaxLatencyTimer — verifies single log line flushed by maxLatencyTimer before logTicker
- [x] TestReporter_BatchSizeFlush — verifies batch size threshold triggers immediate flush
- [x] TestReporter_StateNotifyFlush — verifies step transition triggers immediate state flush
- [x] TestReporter_EphemeralRunnerDeletion — verifies Close/RunDaemon race safety
- [x] TestReporter_RunDaemonClose_Race — verifies concurrent Close safety

Reviewed-on: https://gitea.com/gitea/act_runner/pulls/819
Reviewed-by: Nicolas <173651+bircni@noreply.gitea.com>
Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Co-committed-by: Bo-Yi Wu <appleboy.tw@gmail.com>
2026-04-14 11:29:25 +00:00

275 lines
8.7 KiB
Go

// Copyright 2022 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package run
import (
"context"
"encoding/json"
"fmt"
"maps"
"os"
"path/filepath"
"strings"
"sync"
"time"
runnerv1 "code.gitea.io/actions-proto-go/runner/v1"
"connectrpc.com/connect"
"github.com/docker/docker/api/types/container"
"github.com/nektos/act/pkg/artifactcache"
"github.com/nektos/act/pkg/common"
"github.com/nektos/act/pkg/model"
"github.com/nektos/act/pkg/runner"
log "github.com/sirupsen/logrus"
"gitea.com/gitea/act_runner/internal/pkg/client"
"gitea.com/gitea/act_runner/internal/pkg/config"
"gitea.com/gitea/act_runner/internal/pkg/labels"
"gitea.com/gitea/act_runner/internal/pkg/report"
"gitea.com/gitea/act_runner/internal/pkg/ver"
)
// Runner runs the pipeline.
type Runner struct {
name string
cfg *config.Config
client client.Client
labels labels.Labels
envs map[string]string
runningTasks sync.Map
}
func NewRunner(cfg *config.Config, reg *config.Registration, cli client.Client) *Runner {
ls := labels.Labels{}
for _, v := range reg.Labels {
if l, err := labels.Parse(v); err == nil {
ls = append(ls, l)
}
}
envs := make(map[string]string, len(cfg.Runner.Envs))
maps.Copy(envs, cfg.Runner.Envs)
if cfg.Cache.Enabled == nil || *cfg.Cache.Enabled {
if cfg.Cache.ExternalServer != "" {
envs["ACTIONS_CACHE_URL"] = cfg.Cache.ExternalServer
} else {
cacheHandler, err := artifactcache.StartHandler(
cfg.Cache.Dir,
cfg.Cache.Host,
cfg.Cache.Port,
log.StandardLogger().WithField("module", "cache_request"),
)
if err != nil {
log.Errorf("cannot init cache server, it will be disabled: %v", err)
// go on
} else {
envs["ACTIONS_CACHE_URL"] = cacheHandler.ExternalURL() + "/"
}
}
}
// set artifact gitea api
artifactGiteaAPI := strings.TrimSuffix(cli.Address(), "/") + "/api/actions_pipeline/"
envs["ACTIONS_RUNTIME_URL"] = artifactGiteaAPI
envs["ACTIONS_RESULTS_URL"] = strings.TrimSuffix(cli.Address(), "/")
// Set specific environments to distinguish between Gitea and GitHub
envs["GITEA_ACTIONS"] = "true"
envs["GITEA_ACTIONS_RUNNER_VERSION"] = ver.Version()
return &Runner{
name: reg.Name,
cfg: cfg,
client: cli,
labels: ls,
envs: envs,
}
}
func (r *Runner) Run(ctx context.Context, task *runnerv1.Task) error {
if _, ok := r.runningTasks.Load(task.Id); ok {
return fmt.Errorf("task %d is already running", task.Id)
}
r.runningTasks.Store(task.Id, struct{}{})
defer r.runningTasks.Delete(task.Id)
ctx, cancel := context.WithTimeout(ctx, r.cfg.Runner.Timeout)
defer cancel()
reporter := report.NewReporter(ctx, cancel, r.client, task, r.cfg)
var runErr error
defer func() {
lastWords := ""
if runErr != nil {
lastWords = runErr.Error()
}
_ = reporter.Close(lastWords)
}()
reporter.RunDaemon()
runErr = r.run(ctx, task, reporter)
return nil
}
// getDefaultActionsURL
// when DEFAULT_ACTIONS_URL == "https://github.com" and GithubMirror is not blank,
// it should be set to GithubMirror first.
func (r *Runner) getDefaultActionsURL(task *runnerv1.Task) string {
giteaDefaultActionsURL := task.Context.Fields["gitea_default_actions_url"].GetStringValue()
if giteaDefaultActionsURL == "https://github.com" && r.cfg.Runner.GithubMirror != "" {
return r.cfg.Runner.GithubMirror
}
return giteaDefaultActionsURL
}
func (r *Runner) run(ctx context.Context, task *runnerv1.Task, reporter *report.Reporter) (err error) {
defer func() {
if r := recover(); r != nil {
err = fmt.Errorf("panic: %v", r)
}
}()
reporter.Logf("%s(version:%s) received task %v of job %v, be triggered by event: %s", r.name, ver.Version(), task.Id, task.Context.Fields["job"].GetStringValue(), task.Context.Fields["event_name"].GetStringValue())
workflow, jobID, err := generateWorkflow(task)
if err != nil {
return err
}
plan, err := model.CombineWorkflowPlanner(workflow).PlanJob(jobID)
if err != nil {
return err
}
job := workflow.GetJob(jobID)
reporter.ResetSteps(len(job.Steps))
taskContext := task.Context.Fields
log.Infof("task %v repo is %v %v %v", task.Id, taskContext["repository"].GetStringValue(),
r.getDefaultActionsURL(task),
r.client.Address())
preset := &model.GithubContext{
Event: taskContext["event"].GetStructValue().AsMap(),
RunID: taskContext["run_id"].GetStringValue(),
RunNumber: taskContext["run_number"].GetStringValue(),
RunAttempt: taskContext["run_attempt"].GetStringValue(),
Actor: taskContext["actor"].GetStringValue(),
Repository: taskContext["repository"].GetStringValue(),
EventName: taskContext["event_name"].GetStringValue(),
Sha: taskContext["sha"].GetStringValue(),
Ref: taskContext["ref"].GetStringValue(),
RefName: taskContext["ref_name"].GetStringValue(),
RefType: taskContext["ref_type"].GetStringValue(),
HeadRef: taskContext["head_ref"].GetStringValue(),
BaseRef: taskContext["base_ref"].GetStringValue(),
Token: taskContext["token"].GetStringValue(),
RepositoryOwner: taskContext["repository_owner"].GetStringValue(),
RetentionDays: taskContext["retention_days"].GetStringValue(),
}
if t := task.Secrets["GITEA_TOKEN"]; t != "" {
preset.Token = t
} else if t := task.Secrets["GITHUB_TOKEN"]; t != "" {
preset.Token = t
}
if actionsIDTokenRequestURL := taskContext["actions_id_token_request_url"].GetStringValue(); actionsIDTokenRequestURL != "" {
r.envs["ACTIONS_ID_TOKEN_REQUEST_URL"] = actionsIDTokenRequestURL
r.envs["ACTIONS_ID_TOKEN_REQUEST_TOKEN"] = taskContext["actions_id_token_request_token"].GetStringValue()
task.Secrets["ACTIONS_ID_TOKEN_REQUEST_TOKEN"] = r.envs["ACTIONS_ID_TOKEN_REQUEST_TOKEN"]
}
giteaRuntimeToken := taskContext["gitea_runtime_token"].GetStringValue()
if giteaRuntimeToken == "" {
// use task token to action api token for previous Gitea Server Versions
giteaRuntimeToken = preset.Token
}
r.envs["ACTIONS_RUNTIME_TOKEN"] = giteaRuntimeToken
eventJSON, err := json.Marshal(preset.Event)
if err != nil {
return err
}
maxLifetime := 3 * time.Hour
if deadline, ok := ctx.Deadline(); ok {
maxLifetime = time.Until(deadline)
}
workdirParent := strings.TrimLeft(r.cfg.Container.WorkdirParent, "/")
if r.cfg.Container.BindWorkdir {
// Append the task ID to isolate concurrent jobs from the same repo.
workdirParent = fmt.Sprintf("%s/%d", workdirParent, task.Id)
}
workdir := filepath.FromSlash(fmt.Sprintf("/%s/%s", workdirParent, preset.Repository))
runnerConfig := &runner.Config{
// On Linux, Workdir will be like "/<parent_directory>/<owner>/<repo>"
// On Windows, Workdir will be like "\<parent_directory>\<owner>\<repo>"
Workdir: workdir,
BindWorkdir: r.cfg.Container.BindWorkdir,
ActionCacheDir: filepath.FromSlash(r.cfg.Host.WorkdirParent),
ReuseContainers: false,
ForcePull: r.cfg.Container.ForcePull,
ForceRebuild: r.cfg.Container.ForceRebuild,
LogOutput: true,
JSONLogger: false,
Env: r.envs,
Secrets: task.Secrets,
GitHubInstance: strings.TrimSuffix(r.client.Address(), "/"),
AutoRemove: true,
NoSkipCheckout: true,
PresetGitHubContext: preset,
EventJSON: string(eventJSON),
ContainerNamePrefix: fmt.Sprintf("GITEA-ACTIONS-TASK-%d", task.Id),
ContainerMaxLifetime: maxLifetime,
ContainerNetworkMode: container.NetworkMode(r.cfg.Container.Network),
ContainerOptions: r.cfg.Container.Options,
ContainerDaemonSocket: r.cfg.Container.DockerHost,
Privileged: r.cfg.Container.Privileged,
DefaultActionInstance: r.getDefaultActionsURL(task),
PlatformPicker: r.labels.PickPlatform,
Vars: task.Vars,
ValidVolumes: r.cfg.Container.ValidVolumes,
InsecureSkipTLS: r.cfg.Runner.Insecure,
}
rr, err := runner.New(runnerConfig)
if err != nil {
return err
}
executor := rr.NewPlanExecutor(plan)
reporter.Logf("workflow prepared")
// add logger recorders
ctx = common.WithLoggerHook(ctx, reporter)
if !log.IsLevelEnabled(log.DebugLevel) {
ctx = runner.WithJobLoggerFactory(ctx, NullLogger{})
}
execErr := executor(ctx)
reporter.SetOutputs(job.Outputs)
if r.cfg.Container.BindWorkdir {
// Remove the entire task-specific directory (e.g. /workspace/<task_id>).
taskDir := filepath.FromSlash("/" + workdirParent)
if err := os.RemoveAll(taskDir); err != nil {
log.Warnf("failed to clean up workspace %s: %v", taskDir, err)
}
}
return execErr
}
func (r *Runner) Declare(ctx context.Context, labels []string) (*connect.Response[runnerv1.DeclareResponse], error) {
return r.client.Declare(ctx, connect.NewRequest(&runnerv1.DeclareRequest{
Version: ver.Version(),
Labels: labels,
}))
}