[Core] Avoid high concurrency issue with control master #4455
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cblmemo
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Dec 11, 2024
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Thanks for adding this @Michaelvll ! Left some discussions ;)
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| Args: | ||
| ip: The IP address to check | ||
| threshold: Maximum number of allowed concurrent SSH connections |
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stale? seems now the threshold is a constant (but not an arg)
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| # Use pgrep to efficiently find ssh processes and pipe to grep for IP | ||
| cmd = f'pgrep -f ssh | xargs -r ps -p | grep -c {ip}' |
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Is that only tracks the SSH command from local machine? How about the connections from other laptops
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| # The maximum number of concurrent ssh connections to a same node. This is a | ||
| # heuristic value, based on the observation that when the number of concurrent | ||
| # ssh connections to a node with control master is high, new connections through | ||
| # control master will hang. | ||
| _MAX_CONCURRENT_SSH_CONNECTIONS = 32 |
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have you test if this is related to number of cpu?
cg505
reviewed
Dec 11, 2024
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Actually, this cannot fix the issue with the high concurrency. We may need a better solution. : ) |
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When there are high concurrent ssh connection to the same node with control master, it seems any new connection with the control master will hang. We now add a detection to avoid using control master when the total connections are higher than a threshold.
To reproduce:
Tested (run the relevant ones):
bash format.shpytest tests/test_smoke.pypytest tests/test_smoke.py::test_fill_in_the_nameconda deactivate; bash -i tests/backward_compatibility_tests.sh