Warp wrote:

> - Thread 1 gets done and frees the lock. However, it needs the resource
>   immediately again, and locks it again.
> - Thread 2 gets scheduled and tries again to access the resource, but
>   it's locked, so it can't get it.

I don't know the pthread library well, but are you sure its
lock function works by polling? I'd have expected it to wait
for a signal sent by the unlock function and Thread 1 to
get awakened before Thread 2 can lock again.

Also, why should Thread 2 have a higher priority anyway? It
may feel unfair for it to have to wait all the time, but if
both threads lock the resource too frequently one of them
is bound to be waiting all the time, so the throughput
is not helped by fairness.

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