From 7d3672899f86cf87acc8f8d91b5b1a0a0fe0f0ac Mon Sep 17 00:00:00 2001
From: Dmitry Gozman <dgozman@gmail.com>
Date: Mon, 22 Nov 2021 20:08:09 -0800
Subject: [PATCH] fix(tracing): race in stopChunk (#10481)

Consider the following scenario:
- Tracing is started.
- API call is made (e.g. page.waitForResponse), almost finishes, and
  enters onAfterCall where it starts a snapshot.
- tracing.stopChunk is called, and waits for existing actions to finish.
  However, it does so by calling onAfterCall one more time.
- tracing.stopChunk removes instrumentation listener and returns
  to the client.
- Client starts zipping files.
- Original API call finishes the snapshot and saves it to the trace file.

This results in trace file being written to while the zip is still working.
---
 .../src/server/trace/recorder/tracing.ts      | 23 ++++++++++---------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/packages/playwright-core/src/server/trace/recorder/tracing.ts b/packages/playwright-core/src/server/trace/recorder/tracing.ts
index 9620bdfe3f..a3fdfd3a2b 100644
--- a/packages/playwright-core/src/server/trace/recorder/tracing.ts
+++ b/packages/playwright-core/src/server/trace/recorder/tracing.ts
@@ -172,6 +172,18 @@ export class Tracing implements InstrumentationListener, SnapshotterDelegate, Ha
       throw new Error(`Tracing is already stopping`);
     this._isStopping = true;
 
+    if (!this._state || !this._state.recording) {
+      this._isStopping = false;
+      if (save)
+        throw new Error(`Must start tracing before stopping`);
+      return { artifact: null, entries: [] };
+    }
+
+    const state = this._state!;
+    this._context.instrumentation.removeListener(this);
+    if (this._state?.options.screenshots)
+      this._stopScreencast();
+
     for (const { sdkObject, metadata, beforeSnapshot, actionSnapshot, afterSnapshot } of this._pendingCalls.values()) {
       await Promise.all([beforeSnapshot, actionSnapshot, afterSnapshot]);
       let callMetadata = metadata;
@@ -185,17 +197,6 @@ export class Tracing implements InstrumentationListener, SnapshotterDelegate, Ha
       await this.onAfterCall(sdkObject, callMetadata);
     }
 
-    if (!this._state || !this._state.recording) {
-      this._isStopping = false;
-      if (save)
-        throw new Error(`Must start tracing before stopping`);
-      return { artifact: null, entries: [] };
-    }
-
-    const state = this._state!;
-    this._context.instrumentation.removeListener(this);
-    if (state.options.screenshots)
-      this._stopScreencast();
     if (state.options.snapshots)
       await this._snapshotter.stop();