ArrayBuffer concurrent write safety question #53796
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Hi! Lines 2475 to 2476 in 059f2f4 Lines 2497 to 2501 in 059f2f4 Thanks! |
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@nodejs/fs @nodejs/libuv |
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Hi @Sytten Great question! When you see the Node.js code like:
and then later:
you might wonder about the safety concerning concurrent reads using the same ArrayBuffer. Here's what's happening: Reference Counting: Node.js uses a garbage-collected environment (V8 engine). When you pass a buffer to an async libuv operation, Node.js internally increments the reference count for the buffer. This ensures that the buffer will not be garbage collected while the asynchronous operation is pending. The buffer will only be freed when the reference count drops to zero, i.e., after the async operation completes and no other references to the buffer exist. Concurrency: If you make two concurrent read calls using the same ArrayBuffer, both calls will indeed use the same memory space. This is generally unsafe because the reads can overwrite each other, leading to race conditions and corrupted data. Therefore, it is up to the developer to ensure that the same buffer is not used for concurrent read or write operations. Proper handling of concurrent operations (using locks, different buffers, or other synchronization mechanisms) is necessary to prevent such issues. Internal Handling: The Practical Implications Avoid Concurrent Access: You should avoid using the same buffer for multiple concurrent read/write operations. Each async operation should ideally work on a separate buffer to prevent data corruption. Libuv's Role: Libuv handles the actual asynchronous I/O operations. It takes the pointer to the buffer and performs the read/write in the background. Node.js ensures the buffer is valid during this operation by maintaining references. Node.js and libuv are designed to work safely with buffers in asynchronous operations, but concurrent access to the same buffer must be managed by the developer. Ensuring separate buffers for each concurrent operation or implementing proper synchronization will help maintain data integrity. Hope this clears up your doubts! |
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Hi @Sytten
Great question! When you see the Node.js code like:
and then later:
you might wonder about the safety concerning concurrent reads using the same ArrayBuffer. Here's what's happening:
Memory Management and Safety
Reference Counting: Node.js uses a garbage-collected environment (V8 engine). When you pass a buffer to an async libuv operation, Node.js internal…