fixup

Author: ray-chew

runs/icon_etopo_global.py

@@ -744,21 +744,11 @@ def parallel_wrapper(grid, params, reader, writer, chunk_output_dir, clat_rad, c
                 n_workers = batch_config['n_workers']
                 memory_per_worker = f"{int(batch_config['memory_per_worker_gb'])}GB"
 
-                # Calculate threads per worker based on configuration
-                if config['memory_per_cpu_mb'] is not None:
-                    # HPC mode: Distribute total cores evenly across workers
-                    # (Don't use memory_per_cpu_mb to calculate threads - it's unreliable)
-                    threads_per_worker = max(1, config['total_cores'] // n_workers)
-                else:
-                    # Laptop mode: Calculate based on total available resources
-                    # How many workers can we fit given memory constraints?
-                    max_workers_by_memory = max(1, int(
-                        config['total_memory_gb'] / batch_config['memory_per_worker_gb']
-                    ))
-                    # Limit workers to what we actually configured
-                    actual_workers = min(max_workers_by_memory, n_workers)
-                    # Distribute threads evenly across workers
-                    threads_per_worker = max(1, config['total_cores'] // actual_workers)
+                # CRITICAL: threads_per_worker MUST be 1 because HDF5 is not thread-safe
+                # HDF5 was not compiled with --enable-threadsafe on this system.
+                # Even opening different NetCDF files from different threads causes crashes.
+                # Use more workers instead of threads for parallelism.
+                threads_per_worker = 1
 
                 logger.info(f"\n  Starting Dask client for memory batch {mem_batch_idx}:")
                 logger.info(f"    Workers: {n_workers} × {memory_per_worker}")