8000 issue #9654: make `--rocksdb.max-write-buffer-number` work (#9751) · arangodb/arangodb@0f03655 · GitHub 8000
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issue #9654: make --rocksdb.max-write-buffer-number work (#9751)
* issue #9654: make `--rocksdb.max-write-buffer-number` work * fix the logic
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‎CHANGELOG

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@@ -1,6 +1,13 @@
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v3.5.1 (XXXX-XX-XX)
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-------------------
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* Fixed issue #9654: honor value of `--rocksdb.max-write-buffer-number` if it
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is set to at least 9 (which is the recommended value). Ignore it if it is
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set to a lower value than 9, and warn the end user about it.
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Previous versions of ArangoDB always silently ignored the value of this setting
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and effectively hard-coded the value to 9.
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* Fixed internal issue #4378: fix bug in MoveShard::abort which causes a
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duplicate entry in the follower list.
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‎arangod/RocksDBEngine/RocksDBEngine.cpp

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@@ -561,9 +561,18 @@ void RocksDBEngine::start() {
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_options.db_write_buffer_size = opts->_totalWriteBufferSize;
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}
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// this is cfFamilies.size() + 2 ... but _option needs to be set before
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// building cfFamilies
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_options.max_write_buffer_number = 7 + 2;
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if (!application_features::ApplicationServer::server->options()->processingResult().touched("rocksdb.max-write-buffer-number")) {
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// user hasn't explicitly set the number of write buffers, so we use a default value based
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// on the number of column families
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// this is cfFamilies.size() + 2 ... but _option needs to be set before
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// building cfFamilies
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// Update max_write_buffer_number above if you change number of families used
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_options.max_write_buffer_number = 7 + 2;
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} else if (_options.max_write_buffer_number < 7 + 2) {
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// user set the value explicitly, and it is lower than recommended
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_options.max_write_buffer_number = 7 + 2;
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LOG_TOPIC("d5c49", WARN, Logger::ENGINES) << "ignoring value for option `--rocksdb.max-write-buffer-number` because it is lower than recommended";
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}
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// cf options for definitons (dbs, collections, views, ...)
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rocksdb::ColumnFamilyOptions definitionsCF(_options);
@@ -601,8 +610,9 @@ void RocksDBEngine::start() {
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cfFamilies.emplace_back("VPackIndex", vpackFixedPrefCF); // 4
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cfFamilies.emplace_back("GeoIndex", fixedPrefCF); // 5
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cfFamilies.emplace_back("FulltextIndex", fixedPrefCF); // 6
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// DO NOT FORGET TO DESTROY THE CFs ON CLOSE
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// Update max_write_buffer_number above if you change number of families used
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TRI_ASSERT(static_cast<int>(_options.max_write_buffer_number) >= static_cast<int>(cfFamilies.size()));
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// Update max_write_buffer_number above if you change number of families used
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std::vector<rocksdb::ColumnFamilyHandle*> cfHandles;
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size_t const numberOfColumnFamilies = RocksDBColumnFamily::minNumberOfColumnFamilies;

‎lib/ApplicationFeatures/RocksDBOptionFeature.cpp

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@@ -46,7 +46,7 @@ RocksDBOptionFeature::RocksDBOptionFeature(application_features::ApplicationServ
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_transactionLockTimeout(rocksDBTrxDefaults.transaction_lock_timeout),
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_totalWriteBufferSize(rocksDBDefaults.db_write_buffer_size),
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_writeBufferSize(rocksDBDefaults.write_buffer_size),
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_maxWriteBufferNumber(rocksDBDefaults.max_write_buffer_number),
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_maxWriteBufferNumber(7 + 2), // number of column families plus 2
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_maxTotalWalSize(80 << 20),
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_delayedWriteRate(rocksDBDefaults.delayed_write_rate),
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_minWriteBufferNumberToMerge(rocksDBDefaults.min_write_buffer_number_to_merge),

‎lib/ApplicationFeatures/RocksDBOptionFeature.h

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@@ -49,6 +49,7 @@ class RocksDBOptionFeature final : public application_features::ApplicationFeatu
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std::string _walDirectory;
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uint64_t _totalWriteBufferSize;
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uint64_t _writeBufferSize;
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// Update max_write_buffer_number above if you change number of families used
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uint64_t _maxWriteBufferNumber;
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uint64_t _maxTotalWalSize;
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uint64_t _delayedWriteRate;

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