@Internal public class DetectNewPartitionsTracker extends GrowableOffsetRangeTracker
GrowableOffsetRangeTracker.RangeEndEstimatorRestrictionTracker.HasProgress, RestrictionTracker.IsBounded, RestrictionTracker.Progress, RestrictionTracker.TruncateResult<RestrictionT>lastAttemptedOffset, lastClaimedOffset, range| Constructor and Description |
|---|
DetectNewPartitionsTracker(long start) |
| Modifier and Type | Method and Description |
|---|---|
@Nullable SplitResult<OffsetRange> |
trySplit(double fractionOfRemainder)
Splits current restriction based on
fractionOfRemainder. |
getProgress, isBoundedcheckDone, currentRestriction, toString, tryClaimpublic @Nullable SplitResult<OffsetRange> trySplit(double fractionOfRemainder)
RestrictionTrackerfractionOfRemainder.
If splitting the current restriction is possible, the current restriction is split into a
primary and residual restriction pair. This invocation updates the RestrictionTracker.currentRestriction() to be the primary restriction effectively having the current DoFn.ProcessElement execution responsible for performing the work that the primary restriction
represents. The residual restriction will be executed in a separate DoFn.ProcessElement
invocation (likely in a different process). The work performed by executing the primary and
residual restrictions as separate DoFn.ProcessElement invocations MUST be equivalent to
the work performed as if this split never occurred.
The fractionOfRemainder should be used in a best effort manner to choose a primary
and residual restriction based upon the fraction of the remaining work that the current DoFn.ProcessElement invocation is responsible for. For example, if a DoFn.ProcessElement was reading a file with a restriction representing the offset range [100, 200) and has processed up to offset 130 with a fractionOfRemainder of 0.7, the primary and residual restrictions returned would be [100, 179), [179, 200)
(note: currentOffset + fractionOfRemainder * remainingWork = 130 + 0.7 * 70 = 179).
fractionOfRemainder = 0 means a checkpoint is required.
The API is recommended to be implemented for a batch pipeline to improve parallel processing performance.
The API is recommended to be implemented for batch pipeline given that it is very important for pipeline scaling and end to end pipeline execution.
The API is required to be implemented for a streaming pipeline.
trySplit in class GrowableOffsetRangeTrackerfractionOfRemainder - A hint as to the fraction of work the primary restriction should
represent based upon the current known remaining amount of work.SplitResult if a split was possible, otherwise returns null. If the
fractionOfRemainder == 0, a null result MUST imply that the restriction
tracker is done and there is no more work left to do.