Per-thread allocation counters and limits
This tracks the amount of memory allocation by each thread in a
counter stored in the TSO. Optionally, when the counter drops below
zero (it counts down), the thread can be sent an asynchronous
exception: AllocationLimitExceeded. When this happens, given a small
additional limit so that it can handle the exception. See
documentation in GHC.Conc for more details.
Allocation limits are similar to timeouts, but
- timeouts use real time, not CPU time. Allocation limits do not count anything while the thread is blocked or in foreign code.
- timeouts don't re-trigger if the thread catches the exception, allocation limits do.
- timeouts can catch non-allocating loops, if you use -fno-omit-yields. This doesn't work for allocation limits.
I couldn't measure any impact on benchmarks with these changes, even