fix: prevent concurrent subagent file write conflicts in sandbox tools (#1714)

* fix: prevent concurrent subagent file write conflicts Serialize same-path str_replace operations in sandbox tools Guard AioSandbox write_file/update_file with the existing sandbox lock Add regression tests for concurrent str_replace and append races Verify with backend full tests and ruff lint checks * fix(sandbox): Fix the concurrency issue of file operations on the same path in isolated sandboxes. Ensure that different sandbox instances use independent locks for file operations on the same virtual path to avoid concurrency conflicts. Change the lock key from a single path to a composite key of (sandbox.id, path), and add tests to verify the concurrent safety of isolated sandboxes. * feat(sandbox): Extract file operation lock logic to standalone module and fix concurrency issues Extract file operation lock related logic from tools.py into a separate file_operation_lock.py module. Fix data race issues during concurrent str_replace and write_file operations.
2026-05-21 15:36:48 +00:00 · 2026-04-02 15:39:41 +08:00
parent 3aab2445a6
commit a2cb38f62b
7 changed files with 327 additions and 28 deletions
@@ -131,3 +131,53 @@ class TestListDirSerialization:
        result = sandbox.list_dir("/test")
        assert result == ["/a", "/b"]
        assert lock_was_held == [True], "list_dir must hold the lock during exec_command"
+
+
+class TestConcurrentFileWrites:
+    """Verify file write paths do not lose concurrent updates."""
+
+    def test_append_should_preserve_both_parallel_writes(self, sandbox):
+        storage = {"content": "seed\n"}
+        active_reads = 0
+        state_lock = threading.Lock()
+        overlap_detected = threading.Event()
+
+        def overlapping_read_file(path):
+            nonlocal active_reads
+            with state_lock:
+                active_reads += 1
+                snapshot = storage["content"]
+                if active_reads == 2:
+                    overlap_detected.set()
+
+            overlap_detected.wait(0.05)
+
+            with state_lock:
+                active_reads -= 1
+
+            return snapshot
+
+        def write_back(*, file, content, **kwargs):
+            storage["content"] = content
+            return SimpleNamespace(data=SimpleNamespace())
+
+        sandbox.read_file = overlapping_read_file
+        sandbox._client.file.write_file = write_back
+
+        barrier = threading.Barrier(2)
+
+        def writer(payload: str):
+            barrier.wait()
+            sandbox.write_file("/tmp/shared.log", payload, append=True)
+
+        threads = [
+            threading.Thread(target=writer, args=("A\n",)),
+            threading.Thread(target=writer, args=("B\n",)),
+        ]
+
+        for thread in threads:
+            thread.start()
+        for thread in threads:
+            thread.join()
+
+        assert storage["content"] in {"seed\nA\nB\n", "seed\nB\nA\n"}