Files
act_runner/internal/pkg/config/config.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

187 lines
9.3 KiB
Go

// Copyright 2022 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package config
import (
"fmt"
"maps"
"os"
"path/filepath"
"time"
"github.com/joho/godotenv"
log "github.com/sirupsen/logrus"
"gopkg.in/yaml.v3"
)
// Log represents the configuration for logging.
type Log struct {
Level string `yaml:"level"` // Level indicates the logging level.
}
// Runner represents the configuration for the runner.
type Runner struct {
File string `yaml:"file"` // File specifies the file path for the runner.
Capacity int `yaml:"capacity"` // Capacity specifies the capacity of the runner.
Envs map[string]string `yaml:"envs"` // Envs stores environment variables for the runner.
EnvFile string `yaml:"env_file"` // EnvFile specifies the path to the file containing environment variables for the runner.
Timeout time.Duration `yaml:"timeout"` // Timeout specifies the duration for runner timeout.
ShutdownTimeout time.Duration `yaml:"shutdown_timeout"` // ShutdownTimeout specifies the duration to wait for running jobs to complete during a shutdown of the runner.
Insecure bool `yaml:"insecure"` // Insecure indicates whether the runner operates in an insecure mode.
FetchTimeout time.Duration `yaml:"fetch_timeout"` // FetchTimeout specifies the timeout duration for fetching resources.
FetchInterval time.Duration `yaml:"fetch_interval"` // FetchInterval specifies the interval duration for fetching resources.
FetchIntervalMax time.Duration `yaml:"fetch_interval_max"` // FetchIntervalMax specifies the maximum backoff interval when idle.
LogReportInterval time.Duration `yaml:"log_report_interval"` // LogReportInterval specifies the base interval for periodic log flush.
LogReportMaxLatency time.Duration `yaml:"log_report_max_latency"` // LogReportMaxLatency specifies the max time a log row can wait before being sent.
LogReportBatchSize int `yaml:"log_report_batch_size"` // LogReportBatchSize triggers immediate log flush when buffer reaches this size.
StateReportInterval time.Duration `yaml:"state_report_interval"` // StateReportInterval specifies the interval for state reporting.
Labels []string `yaml:"labels"` // Labels specify the labels of the runner. Labels are declared on each startup
GithubMirror string `yaml:"github_mirror"` // GithubMirror defines what mirrors should be used when using github
}
// Cache represents the configuration for caching.
type Cache struct {
Enabled *bool `yaml:"enabled"` // Enabled indicates whether caching is enabled. It is a pointer to distinguish between false and not set. If not set, it will be true.
Dir string `yaml:"dir"` // Dir specifies the directory path for caching.
Host string `yaml:"host"` // Host specifies the caching host.
Port uint16 `yaml:"port"` // Port specifies the caching port.
ExternalServer string `yaml:"external_server"` // ExternalServer specifies the URL of external cache server
}
// Container represents the configuration for the container.
type Container struct {
Network string `yaml:"network"` // Network specifies the network for the container.
NetworkMode string `yaml:"network_mode"` // Deprecated: use Network instead. Could be removed after Gitea 1.20
Privileged bool `yaml:"privileged"` // Privileged indicates whether the container runs in privileged mode.
Options string `yaml:"options"` // Options specifies additional options for the container.
WorkdirParent string `yaml:"workdir_parent"` // WorkdirParent specifies the parent directory for the container's working directory.
ValidVolumes []string `yaml:"valid_volumes"` // ValidVolumes specifies the volumes (including bind mounts) can be mounted to containers.
DockerHost string `yaml:"docker_host"` // DockerHost specifies the Docker host. It overrides the value specified in environment variable DOCKER_HOST.
ForcePull bool `yaml:"force_pull"` // Pull docker image(s) even if already present
ForceRebuild bool `yaml:"force_rebuild"` // Rebuild docker image(s) even if already present
RequireDocker bool `yaml:"require_docker"` // Always require a reachable docker daemon, even if not required by act_runner
DockerTimeout time.Duration `yaml:"docker_timeout"` // Timeout to wait for the docker daemon to be reachable, if docker is required by require_docker or act_runner
BindWorkdir bool `yaml:"bind_workdir"` // BindWorkdir binds the workspace to the host filesystem instead of using Docker volumes. Required for DinD when jobs use docker compose with bind mounts.
}
// Host represents the configuration for the host.
type Host struct {
WorkdirParent string `yaml:"workdir_parent"` // WorkdirParent specifies the parent directory for the host's working directory.
}
// Config represents the overall configuration.
type Config struct {
Log Log `yaml:"log"` // Log represents the configuration for logging.
Runner Runner `yaml:"runner"` // Runner represents the configuration for the runner.
Cache Cache `yaml:"cache"` // Cache represents the configuration for caching.
Container Container `yaml:"container"` // Container represents the configuration for the container.
Host Host `yaml:"host"` // Host represents the configuration for the host.
}
// LoadDefault returns the default configuration.
// If file is not empty, it will be used to load the configuration.
func LoadDefault(file string) (*Config, error) {
cfg := &Config{}
if file != "" {
content, err := os.ReadFile(file)
if err != nil {
return nil, fmt.Errorf("open config file %q: %w", file, err)
}
if err := yaml.Unmarshal(content, cfg); err != nil {
return nil, fmt.Errorf("parse config file %q: %w", file, err)
}
}
compatibleWithOldEnvs(file != "", cfg)
if cfg.Runner.EnvFile != "" {
if stat, err := os.Stat(cfg.Runner.EnvFile); err == nil && !stat.IsDir() {
envs, err := godotenv.Read(cfg.Runner.EnvFile)
if err != nil {
return nil, fmt.Errorf("read env file %q: %w", cfg.Runner.EnvFile, err)
}
if cfg.Runner.Envs == nil {
cfg.Runner.Envs = map[string]string{}
}
maps.Copy(cfg.Runner.Envs, envs)
}
}
if cfg.Log.Level == "" {
cfg.Log.Level = "info"
}
if cfg.Runner.File == "" {
cfg.Runner.File = ".runner"
}
if cfg.Runner.Capacity <= 0 {
cfg.Runner.Capacity = 1
}
if cfg.Runner.Timeout <= 0 {
cfg.Runner.Timeout = 3 * time.Hour
}
if cfg.Cache.Enabled == nil {
b := true
cfg.Cache.Enabled = &b
}
if *cfg.Cache.Enabled {
if cfg.Cache.Dir == "" {
home, _ := os.UserHomeDir()
cfg.Cache.Dir = filepath.Join(home, ".cache", "actcache")
}
}
if cfg.Container.WorkdirParent == "" {
cfg.Container.WorkdirParent = "workspace"
}
if cfg.Host.WorkdirParent == "" {
home, _ := os.UserHomeDir()
cfg.Host.WorkdirParent = filepath.Join(home, ".cache", "act")
}
if cfg.Runner.FetchTimeout <= 0 {
cfg.Runner.FetchTimeout = 5 * time.Second
}
if cfg.Runner.FetchInterval <= 0 {
cfg.Runner.FetchInterval = 2 * time.Second
}
if cfg.Runner.FetchIntervalMax <= 0 {
cfg.Runner.FetchIntervalMax = 60 * time.Second
}
if cfg.Runner.LogReportInterval <= 0 {
cfg.Runner.LogReportInterval = 5 * time.Second
}
if cfg.Runner.LogReportMaxLatency <= 0 {
cfg.Runner.LogReportMaxLatency = 3 * time.Second
}
if cfg.Runner.LogReportBatchSize <= 0 {
cfg.Runner.LogReportBatchSize = 100
}
if cfg.Runner.StateReportInterval <= 0 {
cfg.Runner.StateReportInterval = 5 * time.Second
}
// Validate and fix invalid config combinations to prevent confusing behavior.
if cfg.Runner.FetchIntervalMax < cfg.Runner.FetchInterval {
log.Warnf("fetch_interval_max (%v) is less than fetch_interval (%v), setting fetch_interval_max to fetch_interval",
cfg.Runner.FetchIntervalMax, cfg.Runner.FetchInterval)
cfg.Runner.FetchIntervalMax = cfg.Runner.FetchInterval
}
if cfg.Runner.LogReportMaxLatency >= cfg.Runner.LogReportInterval {
log.Warnf("log_report_max_latency (%v) >= log_report_interval (%v), the max-latency timer will never fire before the periodic ticker; consider lowering log_report_max_latency",
cfg.Runner.LogReportMaxLatency, cfg.Runner.LogReportInterval)
}
// although `container.network_mode` will be deprecated, but we have to be compatible with it for now.
if cfg.Container.NetworkMode != "" && cfg.Container.Network == "" {
log.Warn("You are trying to use deprecated configuration item of `container.network_mode`, please use `container.network` instead.")
if cfg.Container.NetworkMode == "bridge" {
// Previously, if the value of `container.network_mode` is `bridge`, we will create a new network for job.
// But “bridge” is easily confused with the bridge network created by Docker by default.
// So we set the value of `container.network` to empty string to make `act_runner` automatically create a new network for job.
cfg.Container.Network = ""
} else {
cfg.Container.Network = cfg.Container.NetworkMode
}
}
return cfg, nil
}