Files
act_runner/internal/pkg/client/http.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

86 lines
2.1 KiB
Go

// Copyright 2022 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package client
import (
"context"
"crypto/tls"
"net/http"
"strings"
"time"
"code.gitea.io/actions-proto-go/ping/v1/pingv1connect"
"code.gitea.io/actions-proto-go/runner/v1/runnerv1connect"
"connectrpc.com/connect"
)
func getHTTPClient(endpoint string, insecure bool) *http.Client {
transport := &http.Transport{
MaxIdleConns: 10,
MaxIdleConnsPerHost: 10, // All requests go to one host; default is 2 which causes frequent reconnects.
IdleConnTimeout: 90 * time.Second,
}
if strings.HasPrefix(endpoint, "https://") && insecure {
transport.TLSClientConfig = &tls.Config{
InsecureSkipVerify: true,
}
}
return &http.Client{Transport: transport}
}
// New returns a new runner client.
func New(endpoint string, insecure bool, uuid, token, version string, opts ...connect.ClientOption) *HTTPClient {
baseURL := strings.TrimRight(endpoint, "/") + "/api/actions"
opts = append(opts, connect.WithInterceptors(connect.UnaryInterceptorFunc(func(next connect.UnaryFunc) connect.UnaryFunc {
return func(ctx context.Context, req connect.AnyRequest) (connect.AnyResponse, error) {
if uuid != "" {
req.Header().Set(UUIDHeader, uuid)
}
if token != "" {
req.Header().Set(TokenHeader, token)
}
// TODO: version will be removed from request header after Gitea 1.20 released.
if version != "" {
req.Header().Set(VersionHeader, version)
}
return next(ctx, req)
}
})))
httpClient := getHTTPClient(endpoint, insecure)
return &HTTPClient{
PingServiceClient: pingv1connect.NewPingServiceClient(
httpClient,
baseURL,
opts...,
),
RunnerServiceClient: runnerv1connect.NewRunnerServiceClient(
httpClient,
baseURL,
opts...,
),
endpoint: endpoint,
insecure: insecure,
}
}
func (c *HTTPClient) Address() string {
return c.endpoint
}
func (c *HTTPClient) Insecure() bool {
return c.insecure
}
var _ Client = (*HTTPClient)(nil)
// An HTTPClient manages communication with the runner API.
type HTTPClient struct {
pingv1connect.PingServiceClient
runnerv1connect.RunnerServiceClient
endpoint string
insecure bool
}