diff options
author | jannaerin <golden.janna@gmail.com> | 2019-05-16 13:47:12 -0400 |
---|---|---|
committer | jannaerin <golden.janna@gmail.com> | 2019-05-28 14:41:11 -0400 |
commit | da8c0d18e7ba69ef2ce31236d34816f6fbe8cec3 (patch) | |
tree | b6023881844ba9bc1c5800ac8254e5d3261dab0c | |
parent | be431419dbc96abbfb08acc0578a040aba16eba1 (diff) | |
download | mongo-da8c0d18e7ba69ef2ce31236d34816f6fbe8cec3.tar.gz |
SERVER-36443 Clear ChunkManager objects in metadata when no longer in use
-rw-r--r-- | src/mongo/db/s/metadata_manager.cpp | 65 | ||||
-rw-r--r-- | src/mongo/db/s/metadata_manager.h | 9 | ||||
-rw-r--r-- | src/mongo/db/s/metadata_manager_test.cpp | 80 |
3 files changed, 136 insertions, 18 deletions
diff --git a/src/mongo/db/s/metadata_manager.cpp b/src/mongo/db/s/metadata_manager.cpp index 94679545535..b111875db39 100644 --- a/src/mongo/db/s/metadata_manager.cpp +++ b/src/mongo/db/s/metadata_manager.cpp @@ -201,8 +201,11 @@ public: } } - const CollectionMetadata& get() override { - return _metadataTracker->metadata; + // This will only ever refer to the active metadata, so CollectionMetadata should never be + // boost::none + const CollectionMetadata& get() { + invariant(_metadataTracker->metadata); + return _metadataTracker->metadata.get(); } private: @@ -253,12 +256,12 @@ boost::optional<ScopedCollectionMetadata> MetadataManager::getActiveMetadata( // We don't keep routing history for unsharded collections, so if the collection is unsharded // just return the active metadata - if (!atClusterTime || !activeMetadata.isSharded()) { + if (!atClusterTime || !activeMetadata->isSharded()) { return ScopedCollectionMetadata(std::make_shared<RangePreserver>( lg, std::move(self), std::move(activeMetadataTracker))); } - auto chunkManager = activeMetadata.getChunkManager(); + auto chunkManager = activeMetadata->getChunkManager(); auto chunkManagerAtClusterTime = std::make_shared<ChunkManager>( chunkManager->getRoutingHistory(), atClusterTime->asTimestamp()); @@ -275,7 +278,7 @@ boost::optional<ScopedCollectionMetadata> MetadataManager::getActiveMetadata( }; return ScopedCollectionMetadata(std::make_shared<MetadataAtTimestamp>( - CollectionMetadata(chunkManagerAtClusterTime, activeMetadata.shardId()))); + CollectionMetadata(chunkManagerAtClusterTime, activeMetadata->shardId()))); } size_t MetadataManager::numberOfMetadataSnapshots() const { @@ -286,6 +289,18 @@ size_t MetadataManager::numberOfMetadataSnapshots() const { return _metadata.size() - 1; } +int MetadataManager::numberOfEmptyMetadataSnapshots() const { + stdx::lock_guard<stdx::mutex> lg(_managerLock); + + int emptyMetadataSnapshots = 0; + for (const auto& collMetadataTracker : _metadata) { + if (!collMetadataTracker->metadata) + emptyMetadataSnapshots++; + } + + return emptyMetadataSnapshots; +} + void MetadataManager::setFilteringMetadata(CollectionMetadata remoteMetadata) { stdx::lock_guard<stdx::mutex> lg(_managerLock); @@ -304,9 +319,9 @@ void MetadataManager::setFilteringMetadata(CollectionMetadata remoteMetadata) { // If the metadata being installed has a different epoch from ours, this means the collection // was dropped and recreated, so we must entirely reset the metadata state - if (activeMetadata.getCollVersion().epoch() != remoteMetadata.getCollVersion().epoch()) { + if (activeMetadata->getCollVersion().epoch() != remoteMetadata.getCollVersion().epoch()) { LOG(0) << "Updating metadata for collection " << _nss.ns() << " from " - << activeMetadata.toStringBasic() << " to " << remoteMetadata.toStringBasic() + << activeMetadata->toStringBasic() << " to " << remoteMetadata.toStringBasic() << " due to epoch change"; _receivingChunks.clear(); @@ -318,14 +333,14 @@ void MetadataManager::setFilteringMetadata(CollectionMetadata remoteMetadata) { } // We already have the same or newer version - if (activeMetadata.getCollVersion() >= remoteMetadata.getCollVersion()) { - LOG(1) << "Ignoring update of active metadata " << activeMetadata.toStringBasic() + if (activeMetadata->getCollVersion() >= remoteMetadata.getCollVersion()) { + LOG(1) << "Ignoring update of active metadata " << activeMetadata->toStringBasic() << " with an older " << remoteMetadata.toStringBasic(); return; } LOG(0) << "Updating metadata for collection " << _nss.ns() << " from " - << activeMetadata.toStringBasic() << " to " << remoteMetadata.toStringBasic() + << activeMetadata->toStringBasic() << " to " << remoteMetadata.toStringBasic() << " due to version change"; // Resolve any receiving chunks, which might have completed by now @@ -362,18 +377,33 @@ void MetadataManager::_setActiveMetadata(WithLock wl, CollectionMetadata newMeta } void MetadataManager::_retireExpiredMetadata(WithLock lock) { + // Remove entries and schedule orphans for deletion only from the front of _metadata. We cannot + // remove an entry from the middle of _metadata because a previous entry (whose usageCount is + // not 0) could have a query that is actually still accessing those documents. while (_metadata.size() > 1 && !_metadata.front()->usageCounter) { if (!_metadata.front()->orphans.empty()) { LOG(0) << "Queries possibly dependent on " << _nss.ns() << " range(s) finished; scheduling ranges for deletion"; - // It is safe to push orphan ranges from _metadata.back(), even though new queries might - // start any time, because any request to delete a range it maps is rejected. _pushListToClean(lock, std::move(_metadata.front()->orphans)); } _metadata.pop_front(); } + + // To avoid memory build up of ChunkManager objects, we can clear the CollectionMetadata object + // in an entry when its usageCount is 0 as long as it is not the last item in _metadata (which + // is the active metadata). If _metadata is empty, decrementing iter will be out of bounds, so + // we must check that the size is > 1 as well. + if (_metadata.size() > 1) { + auto iter = _metadata.begin(); + while (iter != (--_metadata.end())) { + if ((*iter)->usageCounter == 0) { + (*iter)->metadata = boost::none; + } + ++iter; + } + } } void MetadataManager::toBSONPending(BSONArrayBuilder& bb) const { @@ -406,7 +436,7 @@ void MetadataManager::append(BSONObjBuilder* builder) const { } BSONArrayBuilder amrArr(builder->subarrayStart("activeMetadataRanges")); - for (const auto& entry : _metadata.back()->metadata.getChunks()) { + for (const auto& entry : _metadata.back()->metadata->getChunks()) { BSONObjBuilder obj; ChunkRange r = ChunkRange(entry.first, entry.second); r.append(&obj); @@ -428,7 +458,7 @@ void MetadataManager::_pushListToClean(WithLock, std::list<Deletion> ranges) { auto when = _rangesToClean.add(std::move(ranges)); if (when) { scheduleCleanup( - _executor, _nss, _metadata.back()->metadata.getCollVersion().epoch(), *when); + _executor, _nss, _metadata.back()->metadata->getCollVersion().epoch(), *when); } } @@ -535,14 +565,15 @@ auto MetadataManager::_findNewestOverlappingMetadata(WithLock, ChunkRange const& invariant(!_metadata.empty()); auto it = _metadata.rbegin(); - if ((*it)->metadata.rangeOverlapsChunk(range)) { + if ((*it)->metadata && (*it)->metadata->rangeOverlapsChunk(range)) { return (*it).get(); } ++it; for (; it != _metadata.rend(); ++it) { auto& tracker = *it; - if (tracker->usageCounter && tracker->metadata.rangeOverlapsChunk(range)) { + if (tracker->usageCounter && tracker->metadata && + tracker->metadata->rangeOverlapsChunk(range)) { return tracker.get(); } } @@ -575,7 +606,7 @@ auto MetadataManager::_overlapsInUseCleanups(WithLock, ChunkRange const& range) boost::optional<ChunkRange> MetadataManager::getNextOrphanRange(BSONObj const& from) const { stdx::lock_guard<stdx::mutex> lg(_managerLock); invariant(!_metadata.empty()); - return _metadata.back()->metadata.getNextOrphanRange(_receivingChunks, from); + return _metadata.back()->metadata->getNextOrphanRange(_receivingChunks, from); } } // namespace mongo diff --git a/src/mongo/db/s/metadata_manager.h b/src/mongo/db/s/metadata_manager.h index 4112d0fe4d8..26cb452ac28 100644 --- a/src/mongo/db/s/metadata_manager.h +++ b/src/mongo/db/s/metadata_manager.h @@ -81,6 +81,13 @@ public: */ size_t numberOfMetadataSnapshots() const; + /** + * Returns the number of metadata objects that have been set to boost::none in + * _retireExpiredMetadata(). The actual number may vary after it returns, so this is really only + * useful for unit tests. + */ + int numberOfEmptyMetadataSnapshots() const; + void setFilteringMetadata(CollectionMetadata newMetadata); void clearFilteringMetadata(); @@ -162,7 +169,7 @@ private: invariant(!usageCounter); } - CollectionMetadata metadata; + boost::optional<CollectionMetadata> metadata; std::list<Deletion> orphans; diff --git a/src/mongo/db/s/metadata_manager_test.cpp b/src/mongo/db/s/metadata_manager_test.cpp index ccce39d0521..db701ec0a60 100644 --- a/src/mongo/db/s/metadata_manager_test.cpp +++ b/src/mongo/db/s/metadata_manager_test.cpp @@ -402,5 +402,85 @@ TEST_F(MetadataManagerTest, RangesToCleanMembership) { notifn.abandon(); } +TEST_F(MetadataManagerTest, ClearUnneededChunkManagerObjectsLastSnapshotInList) { + _manager->setFilteringMetadata(makeEmptyMetadata()); + ChunkRange cr1(BSON("key" << 0), BSON("key" << 10)); + ChunkRange cr2(BSON("key" << 30), BSON("key" << 40)); + + auto scm1 = *_manager->getActiveMetadata(_manager, boost::none); + { + _manager->setFilteringMetadata(cloneMetadataPlusChunk(scm1, cr1)); + ASSERT_EQ(_manager->numberOfMetadataSnapshots(), 1UL); + ASSERT_EQ(_manager->numberOfRangesToClean(), 0UL); + + auto scm2 = *_manager->getActiveMetadata(_manager, boost::none); + ASSERT_EQ(scm2->getChunks().size(), 1UL); + _manager->setFilteringMetadata(cloneMetadataPlusChunk(scm2, cr2)); + ASSERT_EQ(_manager->numberOfMetadataSnapshots(), 2UL); + ASSERT_EQ(_manager->numberOfEmptyMetadataSnapshots(), 0); + } + + // The CollectionMetadata in scm2 should be set to boost::none because the object accessing it + // is now out of scope, but that in scm1 should remain + ASSERT_EQ(_manager->numberOfEmptyMetadataSnapshots(), 1); + ASSERT_EQ(_manager->numberOfMetadataSnapshots(), 2UL); + ASSERT_EQ((*_manager->getActiveMetadata(_manager, boost::none))->getChunks().size(), 2UL); +} + +TEST_F(MetadataManagerTest, ClearUnneededChunkManagerObjectSnapshotInMiddleOfList) { + _manager->setFilteringMetadata(makeEmptyMetadata()); + ChunkRange cr1(BSON("key" << 0), BSON("key" << 10)); + ChunkRange cr2(BSON("key" << 30), BSON("key" << 40)); + ChunkRange cr3(BSON("key" << 50), BSON("key" << 80)); + ChunkRange cr4(BSON("key" << 90), BSON("key" << 100)); + + auto scm = *_manager->getActiveMetadata(_manager, boost::none); + _manager->setFilteringMetadata(cloneMetadataPlusChunk(scm, cr1)); + ASSERT_EQ(_manager->numberOfMetadataSnapshots(), 1UL); + ASSERT_EQ(_manager->numberOfRangesToClean(), 0UL); + + auto scm2 = *_manager->getActiveMetadata(_manager, boost::none); + ASSERT_EQ(scm2->getChunks().size(), 1UL); + _manager->setFilteringMetadata(cloneMetadataPlusChunk(scm2, cr2)); + + { + auto scm3 = *_manager->getActiveMetadata(_manager, boost::none); + ASSERT_EQ(scm3->getChunks().size(), 2UL); + _manager->setFilteringMetadata(cloneMetadataPlusChunk(scm3, cr3)); + ASSERT_EQ(_manager->numberOfMetadataSnapshots(), 3UL); + ASSERT_EQ(_manager->numberOfEmptyMetadataSnapshots(), 0); + + /** + * The CollectionMetadata object created when creating scm2 above will be set to boost::none + * when we overrwrite scm2 below. The _metadata list will then look like: + * [ + * CollectionMetadataTracker{ metadata: xxx, orphans: [], usageCounter: 1}, + * CollectionMetadataTracker{ metadata: boost::none, orphans: [], usageCounter: 0}, + * CollectionMetadataTracker{ metadata: xxx, orphans: [], usageCounter: 1}, + * CollectionMetadataTracker{ metadata: xxx, orphans: [], usageCounter: 1} + * ] + */ + scm2 = *_manager->getActiveMetadata(_manager, boost::none); + ASSERT_EQ(scm2->getChunks().size(), 3UL); + _manager->setFilteringMetadata(cloneMetadataPlusChunk(scm2, cr4)); + ASSERT_EQ(_manager->numberOfMetadataSnapshots(), 4UL); + ASSERT_EQ(_manager->numberOfEmptyMetadataSnapshots(), 1); + } + + + /** The CollectionMetadata in scm3 should be set to boost::none because the object accessing it + * is now out of scope. The _metadata list should look like: + * [ + * CollectionMetadataTracker{ metadata: xxx, orphans: [], usageCounter: 1}, + * CollectionMetadataTracker{ metadata: boost::none, orphans: [], usageCounter: 0}, + * CollectionMetadataTracker{ metadata: boost::none, orphans: [], usageCounter: 0}, + * CollectionMetadataTracker{ metadata: xxx, orphans: [], usageCounter: 1} + * ] + */ + + ASSERT_EQ(_manager->numberOfMetadataSnapshots(), 4UL); + ASSERT_EQ(_manager->numberOfEmptyMetadataSnapshots(), 2); +} + } // namespace } // namespace mongo |