CommandQueueMT: Release the lock during commands for single-flusher usages #112506
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RandomShaper
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topic:core
topic:rendering
needs testing
performance
cherrypick:4.4
akien-mga
reviewed
Nov 7, 2025
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| if (unique_flusher) { | ||
| // A single thread will pump; the lock is only needed for the command queue itself. | ||
| lock.temp_unlock(); | ||
| cmd->call(); |
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here cmd is pointing to memory in the command_mem LocalVector. Is there a risk that while unlocked, the vector could resize and invalidate this memory address? If so, I think a different collection type would be needed that has pointer stability around resizes (like a std::deque). Although those types might have less CPU caching benefits.
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You're right about the potential pointer invalidation. However, we're trusting the call-and-back itself is immune to that, so the line below about handling realloc should be enough. It'd be good to prove the former point more formally, though.
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See #112452 for an explanation of why this would be beneficial.
TL;DR Keeping the lock held over the command queue of the rendering server in separate thread mode is not needed because there's a single thread dealing with such server, Therefore, the lock is only needed for thread safety of the command queue itself, which means the lock can be released while commands are run, allowing other threads to add commands without waiting.
Not tested at all due to lack of time...