Environment Variables for The Parallel Engine

Source : publib.boulder.ibm.com


Set the listed environment variables depending on whether your environment meets the conditions stated in each variable.

Network settings

APT_IO_MAXIMUM_OUTSTANDING

If the system connects to multiple processing nodes through a network, set the APT_IO_MAXIMUM_OUTSTANDING environment variable to specify the amount of memory, in bytes, to reserve for the parallel engine on every node for TCP/IP communications. The default value is 2 MB.

If TCP/IP throughput at that setting is so low that there is idle processor time, increment it by doubling the setting until performance improves. If the system is paging, however, or if your job fails with messages about broken pipes or broken TCP connections, the setting is probably too high.

APT_RECVBUFSIZE

If any of the stages within a job has a large number of communication links between nodes, specify this environment variable with the TCP/IP buffer space that is allocated for each connection. Specify the value in bytes.The APT_SENDBUFSIZE and APT_RECVBUFSIZE values are the same. If you set one of these environment variables, the other is automatically set to the same value. These environment variables override the APT_IO_MAXIMUM_OUTSTANDING environment variable that sets the total amount of TCP/IP buffer space that is used by one partition of a stage.

APT_SENDBUFSIZE

If any of the stages within a job has a large number of communication links between nodes, specify this environment variable with the TCP/IP buffer space that is allocated for each connection. Specify the value in bytes.The APT_SENDBUFSIZE and APT_RECVBUFSIZE values are the same. If you set one of these environment variables, the other is automatically set to the same value. These environment variables override the APT_IO_MAXIMUM_OUTSTANDING environment variable that sets the total amount of TCP/IP buffer space that is used by one partition of a stage.

Transform library

If you are working on a non-NFS MPP system, set the APT_COPY_TRANSFORM_OPERATOR environment variable to true to enable Transformer stages to work in this environment.IBM® WebSphere® DataStage® and QualityStage users must have the appropriate privileges to create project directory paths on all the remote nodes at runtime. This environment variable is set to false by default.

Job monitoring

By default, the job monitor uses time-based monitoring in the IBM WebSphere DataStage and QualityStage Director. The job monitor window is updated every five seconds. You can also specify that the monitoring is based on size. For example, the job monitor window is updated based on the number of new entries. To base monitoring on the number of new entries, set a value for the APT_MONITOR_SIZE environment variable. If you override the default setting for the APT_MONITOR_TIME the setting of the APT_MONITOR_SIZE is also overridden.

Transport block size

To automatically calculate the block size for transferring data internally as job runs, set the APT_AUTO_TRANSPORT_BLOCK_SIZE to True.

Alternately, you can specify a specific block size. By default, this environment variable is set to 32768.

Detailed information about jobs

To produce detailed information about jobs as they run, set the APT_DUMP_SCORE value to True. By default, this environment variable is set to False.

C++ compiler

The environment variables APT_COMPILER and APT_LINKER are set at installation time to point to the default locations of the supported compilers. If your compiler is installed on a different computer from the parallel engine, you must change the default environment variables for every project by using the Administrator client.

Temporary directory

By default, the parallel engine uses the C:\tmp directory for some temporary file storage. If you do not want to use this directory, assign the path name to a different directory by using the environment variable TMPDIR.