Deadlock

• This shows a race condition and a deadlock.

• If A is locked in the first section and the if statement branches around the unset lock, threads running the other sections deadlock waiting for the lock to be released.

• Make sure you release your locks.

CALL OMP_INIT_LOCK (LCKA)

C$OMP PARALLEL SECTIONS

C$OMP SECTION

CALL OMP_SET_LOCK(LCKA)

IVAL = DOWORK()

IF (IVAL .EQ. TOL) THEN

CALL OMP_UNSET_LOCK (LCKA)

ELSE

CALL ERROR (IVAL)

ENDIF

C$OMP SECTION

CALL OMP_SET_LOCK(LCKA)

CALL USE_B_and_A (RES)

CALL OMP_UNSET_LOCK(LCKA)

C$OMP END SECTIONS

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