Fix spurious restart writes caused by incorrect stop_alarm ring time#414
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In ModelSetRunClock, the stop_alarm was created using the driver clock's stopTime, which is just one coupling step ahead (currTime + driver_timestep), not the end of the simulation. This caused the alarm to ring on the first ocean coupling step, triggering spurious restart and rpointer file writes whenever write_restart_at_endofrun was enabled. The bug manifests in fully coupled (B) cases where the driver timestep (set by the fastest component, e.g., atmosphere at 1800s) differs from the ocean coupling interval (3600s). Fix: For CESM-coupled runs, use the model clock's stopTime (captured before ModelSetRunClock overwrites it), which holds the NUOPC-initialized end-of-run time. The non-CESM path is left unchanged for NOAA-EMC to address independently, preferably by removing the cesm_coupled branching this commit adds.
gustavo-marques
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Mar 27, 2026
mnlevy1981
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Apr 2, 2026
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mnlevy1981
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LGTM - I'm trusting the testing done by @alperaltuntas and @gustavo-marques, but I like the if (cesm_coupled) block to ensure we don't change behavior in other models that rely on the NUOPC cap
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In ModelSetRunClock, the stop_alarm was created using the driver clock's stopTime, which is just one coupling step ahead (currTime + driver_timestep), not the end of the simulation. This caused the alarm to ring on the first ocean coupling step, triggering spurious restart and rpointer file writes whenever write_restart_at_endofrun was enabled.
The bug manifests in fully coupled (B) cases where the driver timestep (set by the fastest component, e.g., atmosphere at 1800s) differs from the ocean coupling interval (3600s).
Fix: For CESM-coupled runs, use the model clock's stopTime (captured before ModelSetRunClock overwrites it), which holds the NUOPC-initialized end-of-run time. The non-CESM path is left unchanged for NOAA-EMC to address independently, preferably by removing the cesm_coupled branching this commit adds.
Fixes: #341
Testing: fast_mom.derecho (b4b)