#221: a test for more lock waiters than the pool has threads - #222
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Eight coroutines take one lock in turn with UV_THREADPOOL_SIZE=4, each holding it across a suspension point so the waiters really overlap. Against the thread-pool flock the run never finishes; the file ends up with eight lines instead. The lock itself is checked, not only the deadlock: a waiter says so when flock() returns false, and each compares the file size across its own suspension, so a lock granted twice is reported rather than appended over. Removing the flock calls from the body turns the test red — six of eight waiters see another writer. 081 described the locker as blocked in the thread pool, which is no longer where it waits.
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The regression test for #221. The engine side is merged:
true-async/php-src#18 landed on
true-async, andtrue-asyncis merged intotrue-async-stable, so this test now runs against a build that carries the fix.Eight coroutines take one lock in turn with
UV_THREADPOOL_SIZE=4, each holding it acrossa suspension point so that the waiters really overlap. Against the thread-pool
flocktherun never finishes — run-tests kills it on the timeout — because the holder's own write
needs a pool thread and the waiters have taken them all. With the fix the file ends up
with eight lines.
The test belongs here rather than in
ext/standard/tests/file: it needs coroutines, andwhat it pins is the async runtime's promise that waiting for a lock costs no thread.