Baohe Zhang created SPARK-34779:
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Summary: ExecutoMetricsPoller should keep stage entry in stageTCMP
until a heartbeat occurs
Key: SPARK-34779
URL: https://issues.apache.org/jira/browse/SPARK-34779
Project: Spark
Issue Type: Improvement
Components: Spark Core
Affects Versions: 3.1.1, 3.1.0, 3.0.2, 3.0.1, 3.0.0
Reporter: Baohe Zhang
The current implementation of ExecutoMetricsPoller uses task count in each
stage to decide whether to keep a stage entry or not. In the case of the
executor only has 1 core, it may have these issues:
# Peak metrics missing (due to stage entry being removed within a heartbeat
interval)
# Unnecessary and frequent hashmap entry removal and insertion.
Assuming an executor with 1 core has 2 tasks (task1 and task2, both belong to
stage (0,0)) to execute in a heartbeat interval, the workflow in current
ExecutorMetricsPoller implementation would be:
1. task1 start -> stage (0, 0) entry created in stageTCMP, task count increment
to1
2. 1st poll() -> update peak metrics of stage (0, 0)
3. task1 end -> stage (0, 0) task count decrement to 0, stage (0, 0) entry
removed, peak metrics lost.
4. task2 start -> stage (0, 0) entry created in stageTCMP, task count increment
to1
5. 2nd poll() -> update peak metrics of stage (0, 0)
6. task2 end -> stage (0, 0) task count decrement to 0, stage (0, 0) entry
removed, peak metrics lost
7. heartbeat() -> empty or inaccurate peak metrics for stage(0,0) reported.
We can fix the issue by keeping entries with task count = 0 in stageTCMP map
until a heartbeat occurs. At the heartbeat, after reporting the peak metrics
for each stage, we scan each stage in stageTCMP and remove entries with task
count = 0.
After the fix, the workflow would be:
1. task1 start -> stage (0, 0) entry created in stageTCMP, task count increment
to1
2. 1st poll() -> update peak metrics of stage (0, 0)
3. task1 end -> stage (0, 0) task count decrement to 0,but the entry (0,0)
still remain.
4. task2 start -> task count of stage (0,0) increment to1
5. 2nd poll() -> update peak metrics of stage (0, 0)
6. task2 end -> stage (0, 0) task count decrement to 0,but the entry (0,0)
still remain.
7. heartbeat() -> accurate peak metrics for stage (0, 0) reported. Remove
entry for stage (0,0) in stageTCMP because its task count is 0.
How to verify the behavior?
Submit a job with a custom polling interval (e.g., 2s) and
spark.executor.cores=1 and check the debug logs of ExecutoMetricsPoller.
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