You have several threads competing for the same resource.

Try moving your 'import arcpy' statement into the target of the multiprocessing. You'll ensure arcpy is working with it's own set of environment variables and memory.

It sounds absurd, but even though you are setting environment variables in the Multiprocess target method, python is still using a shared memory space to manage the arcpy module and therefore any variables you set.

Arcpy isn't thread safe. It was always intended to be used within a single process. But there are workarounds.

UPDATE

Sorry for the ambiguity. My suggestion was to import arcpy within the target for new process.

def _multiprocessing_target(args):
    import arcpy
    ...code

You have several threads competing for the same resource.

Try moving your 'import arcpy' statement into the target of the multiprocessing. You'll ensure arcpy is working with it's own set of environment variables and memory.

It sounds absurd, but even though you are setting environment variables in the Multiprocess target method, python is still using a shared memory space to manage the arcpy module and therefore any variables you set.

Arcpy isn't thread safe. It was always intended to be used within a single process. But there are workarounds.

My suggestion was to import arcpy within the target for new process.

def _multiprocessing_target(args):
    import arcpy
    ...code

You have several threads competing for the same resource.

Try moving your 'import arcpy' statement into the target of the multiprocessing. You'll ensure arcpy is working with it's own set of environment variables and memory.

It sounds absurd, but even though you are setting environment variables in the Multiprocess target method, python is still using a shared memory space to manage the arcpy module and therefore any variables you set.

Arcpy isn't thread safe. It was always intended to be used within a single process. But there are workarounds.

You have several threads competing for the same resource.

Try moving your 'import arcpy' statement into the target of the multiprocessing. You'll ensure arcpy is working with it's own set of environment variables and memory.

It sounds absurd, but even though you are setting environment variables in the Multiprocess target method, python is still using a shared memory space to manage the arcpy module and therefore any variables you set.

Arcpy isn't thread safe. It was always intended to be used within a single process. But there are workarounds.

UPDATE

Sorry for the ambiguity. My suggestion was to import arcpy within the target for new process.

def _multiprocessing_target(args):
    import arcpy
    ...code