The PostCommit Python Examples Flink job is flaky

[github-actions]

The PostCommit Python Examples Flink is failing over 50% of the time.
Please visit https://github.com/apache/beam/actions/workflows/beam_PostCommit_Python_Examples_Flink.yml?query=is%3Afailure+branch%3Amaster to see all failed workflow runs.
See also Grafana statistics: http://metrics.beam.apache.org/d/CTYdoxP4z/ga-post-commits-status?orgId=1&viewPanel=8&var-Workflow=PostCommit%20Python%20Examples%20Flink

[liferoad]

INFO     apache_beam.utils.subprocess_server:subprocess_server.py:213 Caused by: java.io.IOException: Insufficient number of network buffers: required 16, but only 8 available. The total number of network buffers is currently set to 2048 of 32768 bytes each. You can increase this number by setting the configuration keys 'taskmanager.memory.network.fraction', 'taskmanager.memory.network.min', and 'taskmanager.memory.network.max'.
INFO     apache_beam.utils.subprocess_server:subprocess_server.py:213 	at org.apache.flink.runtime.io.network.buffer.NetworkBufferPool.internalCreateBufferPool(NetworkBufferPool.java:495)
INFO     apache_beam.utils.subprocess_server:subprocess_server.py:213 	at org.apache.flink.runtime.io.network.buffer.NetworkBufferPool.createBufferPool(NetworkBufferPool.java:468)
INFO     apache_beam.utils.subprocess_server:subprocess_server.py:213 	at org.apache.flink.runtime.io.network.partition.ResultPartitionFactory.lambda$createBufferPoolFactory$1(ResultPartitionFactory.java:379)
INFO     apache_beam.utils.subprocess_server:subprocess_server.py:213 	at org.apache.flink.runtime.io.network.partition.ResultPartition.setup(ResultPartition.java:158)
INFO     apache_beam.utils.subprocess_server:subprocess_server.py:213 	at org.apache.flink.runtime.taskmanager.Task.setupPartitionsAndGates(Task.java:969)
INFO     apache_beam.utils.subprocess_server:subprocess_server.py:213 	at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:658)
INFO     apache_beam.utils.subprocess_server:subprocess_server.py:213 	at org.apache.flink.runtime.taskmanager.Task.run(Task.java:566)
INFO     apache_beam.utils.subprocess_server:subprocess_server.py:213 	at java.base/java.lang.Thread.run(Thread.java:829)

[github-actions]

Reopening since the workflow is still flaky

[liferoad]

No useful logs from the failed workflows.

[liferoad]

Looks like some mem issue:

The node was low on resource: memory. Threshold quantity: 100Mi, available: 74432Ki. Container runner was using 58152720Ki, request is 3Gi, has larger consumption of memory. Container docker was using 43668Ki, request is 0, has larger consumption of memory.