CA-394882,CA-394883: Fix task server race condition, and testcase race condition #5737
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The code in 'next_task_id' has a race condition: ``` (* thread 1 *) 42 = !counter (* fine, integer ref operations are atomic on OCaml 4 *) result = string_of_int (* allocates, may process pending signals and switch to another OCaml thread! *) (* thread 2 *) 42 = !counter result = "42" incr counter (* fine, this is atomic on OCaml 4 *) result (* thread 2 got task id 42 *) (* thread 1 *) incr counter (* fine, this is atomic on OCaml 4 *) result (* thread 1 got same task id as thread 2: 42! *) ``` The solution is to: * use mutexes, * rearrange the order of operations to avoid allocations in the critical section * use Atomic.fetch_and_add (also makes this future proof for OCaml 5) Signed-off-by: Edwin Török <edwin.torok@cloud.com>
The previous unit test step has created some tasks, and deleted them when completed. However it didn't look at events. The next step was waiting for some newly created tasks to complete and looking at events. But it was processing all events, even those that it wasn't watching for. These events may have referred to tasks that were already deleted. Fix the code to only query the state of the tasks that we are waiting for (if these go missing, it is a bug). Signed-off-by: Edwin Török <edwin.torok@cloud.com>
psafont
approved these changes
Jun 26, 2024
lindig
approved these changes
Jun 26, 2024
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