vaijosh commented on code in PR #3164:
URL: https://github.com/apache/hugegraph/pull/3164#discussion_r4000153725
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hugegraph-store/hg-store-core/src/main/java/org/apache/hugegraph/store/business/BusinessHandlerImpl.java:
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@@ -154,6 +165,18 @@ public class BusinessHandlerImpl implements
BusinessHandler {
private final InnerKeyCreator keyCreator;
private final Semaphore semaphore = new Semaphore(1);
+ /* Bounds how long dbCompaction() waits to acquire compactionRangeLock
when a snapshot
+ save is holding it. saveSnapshot() is a RocksDB Checkpoint (hard-links
existing SST
+ files, no data copy) plus a partial checksum read, so the lock is
normally held for
+ well under a second, at most a few seconds under a slow/busy disk. 10s
gives generous
+ margin over that expected hold time while keeping a stuck snapshot save
from blocking
+ compaction for long: if the wait is exceeded, dbCompaction just skips
this pass and
+ relies on the next trigger (PD instruction, REST call, etc.) to retry -
see the
Review Comment:
@bitflicker64
I think the wording in the comment is correct. It says:
dbCompaction just skips this pass -- Means “If the lock wait is exceeded,
dbCompaction() gives up on that attempt and skips the current pass.”
“It relies on the next trigger (PD instruction, REST call, etc.).” -- Means
that compaction does not spin or schedule an immediate internal retry in that
code path. If tryLock() times out, the current attempt ends, and a later
external trigger—such as a PD instruction, REST call, or another compaction
request—can start a new attempt.
Nowhere do we mention an “internal retry in that code path.”
Earlier I had removed the line because it looked redundant at that place.
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