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Coordinated Restore at Checkpoint Exceptions

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Checkpoint Exceptions

During the creation of a checkpoint, the system can throw exceptions if an open file or socket prevented the creation of the checkpoint. When a checkpoint can be created successfully, the JVM stops running (default behavior). But in case of a checkpoint exception, the application continues to run.

The possible exceptions can be found in the sources of the project on GitHub.

CheckpointOpenSocketException

  • The checkpoint can’t be created because there is a listening socket.

  • The exception may be reported several times, for each socket independently.

  • The exception message specifies socket local and remote address and port.

 
CheckpointOpenSocketException: tcp6 localAddr :: localPort 8080 remoteAddr :: remotePort 0

CheckpointOpenFileException

  • The checkpoint can’t be created because there is an open file.

  • The exception message specifies the path to the file.

 
CheckpointOpenFileException: /home/user/someFile.txt

CheckpointOpenResourceException

  • There is some native resource open that is not socket nor file.

Restore Exceptions

Additional Mappings Needed for Large Applications

The JVM may need more virtual memory areas than the Linux default of 65530 to restore a checkpoint of a large application. A value of 10,000,000 (ten million) is recommended for systems with a RAM size of up to 2.5 TBytes (2560 GBytes). To set the recommended value, complete the following steps:

Add the following line to the file /etc/sysctl.conf:

 
vm.max_map_count=10000000

To activate the setting without reboot, run:

 
sudo sysctl -p

To check the setting on any system, type:

 
cat /proc/sys/vm/max_map_count