https://community.intel.com/t5/Intel-Fortran-Compiler/Issue-with-OMP-ATOMIC-UPDATE-CAPTURE/m-p/1746860#M178805 <P>The following code (compiled on Windows with ifx 2026.0.0 and using the compiler option \Qopenmp) freezes after the first WRITE statement, usually after a small number of iterations on the loop index I. I can't figure out what is wrong here, and I am inclined to report this as a bug.</P><P>This is a showstopper for us, thus any alternative to the pattern shown here would be very much appreciated!</P><P>&nbsp;</P><LI-CODE lang="fortran">PROGRAM OMP_ATOMIC_TEST USE OMP_LIB IMPLICIT NONE INTEGER :: I, ERROR INTEGER, SAVE :: ERROR_LOCAL, ERROR_TEMP !$OMP THREADPRIVATE(ERROR_LOCAL, ERROR_TEMP) CALL OMP_SET_NUM_THREADS(10) DO I = 1, 20 ! The purpose of this loop is to demonstrate the issue, it is unrelated ! to the following PARALLEL region. The code will freeze for some value ! of I, after having issued the first WRITE statement, and inside the ! ATOMIC UPDATE CAPTURE region. !$OMP PARALLEL IF (OMP_GET_THREAD_NUM() == 1) THEN WRITE(*, *) 'Begin ATOMIC CAPTURE region ', I !$OMP ATOMIC UPDATE CAPTURE ERROR_TEMP = ERROR ! Capture ERROR = 1 ! Update !$OMP END ATOMIC ERROR_LOCAL = ERROR_TEMP WRITE(*, *) 'End ATOMIC CAPTURE region' END IF !$OMP END PARALLEL END DO END PROGRAM OMP_ATOMIC_TEST</LI-CODE><P>&nbsp;</P> Tue, 05 May 2026 19:11:14 GMT OP1 2026-05-05T19:11:14Z https://community.intel.com/t5/Intel-Fortran-Compiler/Issue-with-OMP-ATOMIC-UPDATE-CAPTURE/m-p/1746860#M178805 <P>The following code (compiled on Windows with ifx 2026.0.0 and using the compiler option \Qopenmp) freezes after the first WRITE statement, usually after a small number of iterations on the loop index I. I can't figure out what is wrong here, and I am inclined to report this as a bug.</P><P>This is a showstopper for us, thus any alternative to the pattern shown here would be very much appreciated!</P><P>&nbsp;</P><LI-CODE lang="fortran">PROGRAM OMP_ATOMIC_TEST USE OMP_LIB IMPLICIT NONE INTEGER :: I, ERROR INTEGER, SAVE :: ERROR_LOCAL, ERROR_TEMP !$OMP THREADPRIVATE(ERROR_LOCAL, ERROR_TEMP) CALL OMP_SET_NUM_THREADS(10) DO I = 1, 20 ! The purpose of this loop is to demonstrate the issue, it is unrelated ! to the following PARALLEL region. The code will freeze for some value ! of I, after having issued the first WRITE statement, and inside the ! ATOMIC UPDATE CAPTURE region. !$OMP PARALLEL IF (OMP_GET_THREAD_NUM() == 1) THEN WRITE(*, *) 'Begin ATOMIC CAPTURE region ', I !$OMP ATOMIC UPDATE CAPTURE ERROR_TEMP = ERROR ! Capture ERROR = 1 ! Update !$OMP END ATOMIC ERROR_LOCAL = ERROR_TEMP WRITE(*, *) 'End ATOMIC CAPTURE region' END IF !$OMP END PARALLEL END DO END PROGRAM OMP_ATOMIC_TEST</LI-CODE><P>&nbsp;</P> Tue, 05 May 2026 19:11:14 GMT https://community.intel.com/t5/Intel-Fortran-Compiler/Issue-with-OMP-ATOMIC-UPDATE-CAPTURE/m-p/1746860#M178805 OP1 2026-05-05T19:11:14Z