fix(browser): prevent stdio buffer blocking in Docker environments by stephenschoettler · Pull Request #27899 · openclaw/openclaw

stephenschoettler · 2026-02-26T20:16:40Z

Fixes browser automation failures in Docker by changing Chrome spawn configuration from stdio: "pipe" to stdio: ["ignore", "ignore", "ignore"].

Problem: When using stdio: "pipe", Chrome's stdout/stderr buffers fill up (~64KB limit) and block the process, preventing CDP from becoming reachable within the timeout window.

Solution: Discard Chrome's output instead of piping it. The codebase doesn't consume Chrome's stdout/stderr anyway, so there's no functional loss.

Result: CDP becomes reachable within ~500ms of Chrome startup in Docker.

Tested manually in Docker with Playwright Chromium on Debian 12.

greptile-apps · 2026-02-26T20:20:02Z

Greptile Summary

This PR contains two separate bug fixes:

Browser stdio fix (chrome.ts): Changed Chrome spawn configuration from stdio: "pipe" to stdio: ["ignore", "ignore", "ignore"] to prevent buffer blocking in Docker environments. The codebase doesn't consume Chrome's stdout/stderr streams anywhere, so discarding them is safe and resolves the CDP timeout issue.
Null guard fix (usage.ts, session-cost-usage.ts): Added optional chaining and nullish coalescing to usage sort comparators to prevent crashes when totals is undefined. The fix prevents "Cannot read properties of undefined" errors in production.

Note: The PR title only mentions the browser fix, but includes the unrelated usage fix as well. According to the project's guidelines (CLAUDE.md), unrelated changes should typically be in separate PRs. Both fixes are valid, but bundling them may make the PR history harder to track.

Confidence Score: 4/5

This PR is safe to merge with low risk
Both fixes address real bugs and are technically correct. The stdio change is well-justified and doesn't break any existing functionality (verified that Chrome stdout/stderr are unused). The null guards are defensive programming that prevent actual crashes. Score is 4 instead of 5 due to: (1) bundling two unrelated fixes in one PR, which goes against project guidelines, and (2) missing test coverage for the fixes.
No files require special attention

_{Last reviewed commit: 200f8c0}

openclaw-barnacle · 2026-03-04T04:02:57Z

This pull request has been automatically marked as stale due to inactivity.
Please add updates or it will be closed.

stephenschoettler · 2026-03-04T23:01:22Z

Note: the install-smoke failure blocking PR #31192 is the same src/browser/chrome.ts stdin type mismatch that this PR fixes. Merging this PR (#27899) should unblock #31192's CI as well.

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chatgpt-codex-connector · 2026-03-22T22:03:54Z

src/browser/chrome.ts


    return spawn(exe.path, args, {
-      stdio: "pipe",
+      stdio: ["ignore", "ignore", "ignore"],


Keep Chrome stderr piped for startup failures

When Chrome exits before CDP comes up — for example because a container is missing shared libraries or still needs browser.noSandbox: true — this change removes the only actionable diagnostics we surface. launchOpenClawChrome still installs proc.stderr?.on("data") and includes stderrHint in the thrown error (src/browser/chrome.ts:379-413), but with fd 2 set to "ignore" proc.stderr is always null, so these failures now degrade to a generic timeout. Because stderr was already being drained, only stdout needed to stop piping to avoid the Docker backpressure issue.

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chatgpt-codex-connector · 2026-03-23T00:26:01Z

src/browser/chrome.ts

+    // the tuple overload resolution varies across @types/node versions.
    return spawn(exe.path, args, {
-      stdio: "pipe",
+      stdio: ["ignore", "ignore", "pipe"],


Ignore bootstrap stderr too to fix first-run Docker launches

When needsBootstrap is true (first run, or after the profile files are missing), launchOpenClawChrome() reuses spawnOnce() for the bootstrap process but does not attach a data listener until the later “real” launch. Because fd 2 is still pipe here, a noisy Chromium startup in containers can fill bootstrap.stderr and stall before Local State/Preferences are created, so the Docker deadlock this patch is fixing still reproduces on fresh profiles. Discarding or draining stderr for the bootstrap run would make the fix cover first-run launches as well.

Useful? React with 👍 / 👎.

Prevents crash when totals is undefined in byModel/byProvider/byAgent sort comparators. Fixes 'Cannot read properties of undefined (reading totalTokens)' crash that causes context overflow in active sessions.

… compat The stdio tuple overload resolves differently across @types/node versions (v20 vs v24/v25). Cast the spawn() result to ChildProcessWithoutNullStreams to ensure proc.stderr?.on/off type-checks regardless of installed @types/node.

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chatgpt-codex-connector · 2026-03-23T00:50:58Z

src/browser/chrome.ts

+    // the tuple overload resolution varies across @types/node versions.
    return spawn(exe.path, args, {
-      stdio: "pipe",
+      stdio: ["ignore", "ignore", "pipe"],


Keep draining stderr after Chrome startup

When Chrome reaches CDP readiness we remove the only stderr listener (src/browser/chrome.ts:428-430), but this change still leaves fd 2 configured as "pipe". The comment at src/browser/chrome.ts:392-393 already notes that long-lived Chrome processes can emit periodic warnings; in Docker/root setups those warnings will now accumulate in the undrained pipe until it fills, at which point later writes block again. So this only fixes startup backpressure on stdout — long-running browser sessions are still vulnerable to the same stdio saturation issue once enough stderr is produced.

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openclaw-barnacle · 2026-03-31T04:25:40Z

This pull request has been automatically marked as stale due to inactivity.
Please add updates or it will be closed.

openclaw-barnacle bot added gateway Gateway runtime size: XS labels Feb 26, 2026

openclaw-barnacle bot added the stale Marked as stale due to inactivity label Mar 4, 2026

stephenschoettler mentioned this pull request Mar 4, 2026

fix(delivery-queue): increment retryCount on entries deferred when time budget exceeded #31192

Merged

openclaw-barnacle bot removed the stale Marked as stale due to inactivity label Mar 5, 2026

stephenschoettler force-pushed the fix/docker-browser-stdio branch 2 times, most recently from 7ef53df to bd8bda0 Compare March 22, 2026 22:01

chatgpt-codex-connector bot reviewed Mar 22, 2026

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stephenschoettler force-pushed the fix/docker-browser-stdio branch from bd8bda0 to ef829e8 Compare March 23, 2026 00:22

chatgpt-codex-connector bot reviewed Mar 23, 2026

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stephenschoettler added 3 commits March 22, 2026 17:46

fix: add null guards to usage sort comparators

86507c4

Prevents crash when totals is undefined in byModel/byProvider/byAgent sort comparators. Fixes 'Cannot read properties of undefined (reading totalTokens)' crash that causes context overflow in active sessions.

fix(browser): prevent stdio buffer blocking in Docker environments

c72eb11

stephenschoettler force-pushed the fix/docker-browser-stdio branch from ef829e8 to 036d09f Compare March 23, 2026 00:47

chatgpt-codex-connector bot reviewed Mar 23, 2026

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openclaw-barnacle bot added the stale Marked as stale due to inactivity label Mar 31, 2026

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fix(browser): prevent stdio buffer blocking in Docker environments#27899

fix(browser): prevent stdio buffer blocking in Docker environments#27899
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