Add lower bound for translog flush threshold #28382
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If the translog flush threshold is too small (eg. smaller than the translog header), we may repeatedly flush even there is no uncommitted operation because the shouldFlush condition can still be true after flushing. This is currently avoided by adding an extra guard against the uncommitted operations. However, this extra guard makes the shouldFlush complicated. This commit replaces that extra guard by a lower bound for translog flush threshold. We keep the lower bound small for convenience in testing. Relates elastic#28350 Relates elastic#23606
bleskes
approved these changes
Feb 1, 2018
| @@ -108,6 +108,7 @@ | |||
| public static final String CHECKPOINT_FILE_NAME = "translog" + CHECKPOINT_SUFFIX; | |||
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| static final Pattern PARSE_STRICT_ID_PATTERN = Pattern.compile("^" + TRANSLOG_FILE_PREFIX + "(\\d+)(\\.tlog)$"); | |||
| public static final int DEFAULT_HEADER_SIZE_IN_BYTES = TranslogWriter.getHeaderLength(UUIDs.randomBase64UUID()); | |||
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can we assert somewhere that this is correct?
| * non-zero value after rolling a new translog generation. This can be avoided by checking the actual uncommitted operations. | ||
| */ | ||
| return uncommittedSizeOfNewCommit < uncommittedSizeOfCurrentCommit && translog.uncommittedOperations() > 0; | ||
| return uncommittedSizeOfNewCommit < uncommittedSizeOfCurrentCommit; |
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can we add an assertion that the uncommitOps is >0 ?
| @@ -219,9 +226,9 @@ | |||
| * generation threshold. However, small thresholds are useful for testing so we | |||
| * do not add a large lower bound here. | |||
| */ | |||
| new ByteSizeValue(64, ByteSizeUnit.BYTES), | |||
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I think we need to adapt the comment above?
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Thanks @bleskes for reviewing. |
dnhatn
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Feb 1, 2018
If the translog flush threshold is too small (eg. smaller than the translog header), we may repeatedly flush even there is no uncommitted operation because the shouldFlush condition can still be true after flushing. This is currently avoided by adding an extra guard against the uncommitted operations. However, this extra guard makes the shouldFlush complicated. This commit replaces that extra guard by a lower bound for translog flush threshold. We keep the lower bound small for convenience in testing. Relates #28350 Relates #23606
clintongormley
added
:Distributed/Distributed
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If the translog flush threshold is too small (eg. smaller than the
translog header), we may repeatedly flush even there is no uncommitted
operation because the shouldFlush condition can still be true after
flushing. This is currently avoided by adding an extra guard against the
uncommitted operations. However, this extra guard makes the shouldFlush
complicated. This commit replaces that extra guard by a lower bound for
translog flush threshold. We keep the lower bound small for convenience
in testing.
Relates #28350
Relates #23779