Deadlock/1

• The following code shows a race condition with deadlock:

• • if A is locked by one thread and B by another - there is a deadlock
  • if the same thread gets both locks, you get a race condition:
    • different behaviour depending on detailed timing of the threads
  • Avoid nesting different locks

call omp_init_lock(lcka)

call omp_init_lock(lckb)

C$omp parallel sections

c$omp section

call omp_set_lock(lcka)

call omp_set_lock(lckb)

call use_A_and_B(res)

call omp_unset_lock(lckb)

call omp_unset_lock(lcka)

c$omp section

call omp_set_lock(lckb)

call omp_set_lock(lcka)

call use_B_and_A(res)

call omp_unset_lock(lcka)

call omp_unset_lock(lckb)

c$omp end parallel sections

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