测试时发现理解这些参数都代表什么意义非常的重要,而且通过参数调优可以提高性能,希望仔细阅读一下每个属性代表的意义!
感谢原作者的整理,转来仅做学习笔记使用
- <span style="font-family:Microsoft YaHei;"><?xml version="1.0"?>
- <?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
- <!--
- /**
- * Copyright 2009 The Apache Software Foundation
- *
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements. See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership. The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- -->
- <configuration>
- <property>
- <name>hbase.rootdir</name>
- <value>file:///tmp/hbase-${user.name}/hbase</value>
- <description>The directory shared by region servers and into
- which HBase persists. The URL should be 'fully-qualified'
- to include the filesystem scheme. For example, to specify the
- HDFS directory '/hbase' where the HDFS instance's namenode is
- running at namenode.example.org on port 9000, set this value to:
- hdfs://namenode.example.org:9000/hbase. By default HBase writes
- into /tmp. Change this configuration else all data will be lost
- on machine restart.
- </description>
- </property>
- <property>
- <name>hbase.master.port</name>
- <value>60000</value>
- <description>The port the HBase Master should bind to.</description>
- </property>
- <property>
- <name>hbase.cluster.distributed</name>
- <value>false</value>
- <description>The mode the cluster will be in. Possible values are
- false for standalone mode and true for distributed mode. If
- false, startup will run all HBase and ZooKeeper daemons together
- in the one JVM.
- </description>
- </property>
- <property>
- <name>hbase.tmp.dir</name>
- <value>/tmp/hbase-${user.name}</value>
- <description>Temporary directory on the local filesystem.
- Change this setting to point to a location more permanent
- than '/tmp' (The '/tmp' directory is often cleared on
- machine restart).
- </description>
- </property>
- <property>
- <name>hbase.master.info.port</name>
- <value>60010</value>
- <description>The port for the HBase Master web UI.
- Set to -1 if you do not want a UI instance run.
- </description>
- </property>
- <property>
- <name>hbase.master.info.bindAddress</name>
- <value>0.0.0.0</value>
- <description>The bind address for the HBase Master web UI
- </description>
- </property>
- <property>
- <name>hbase.client.write.buffer</name>
- <value>2097152</value>
- <description>Default size of the HTable clien write buffer in bytes.
- A bigger buffer takes more memory -- on both the client and server
- side since server instantiates the passed write buffer to process
- it -- but a larger buffer size reduces the number of RPCs made.
- For an estimate of server-side memory-used, evaluate
- hbase.client.write.buffer * hbase.regionserver.handler.count
- </description>
- </property>
- <property>
- <name>hbase.regionserver.port</name>
- <value>60020</value>
- <description>The port the HBase RegionServer binds to.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.info.port</name>
- <value>60030</value>
- <description>The port for the HBase RegionServer web UI
- Set to -1 if you do not want the RegionServer UI to run.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.info.port.auto</name>
- <value>false</value>
- <description>Whether or not the Master or RegionServer
- UI should search for a port to bind to. Enables automatic port
- search if hbase.regionserver.info.port is already in use.
- Useful for testing, turned off by default.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.info.bindAddress</name>
- <value>0.0.0.0</value>
- <description>The address for the HBase RegionServer web UI
- </description>
- </property>
- <property>
- <name>hbase.regionserver.class</name>
- <value>org.apache.hadoop.hbase.ipc.HRegionInterface</value>
- <description>The RegionServer interface to use.
- Used by the client opening proxy to remote region server.
- </description>
- </property>
- <property>
- <name>hbase.client.pause</name>
- <value>1000</value>
- <description>General client pause value. Used mostly as value to wait
- before running a retry of a failed get, region lookup, etc.</description>
- </property>
- <property>
- <name>hbase.client.retries.number</name>
- <value>10</value>
- <description>Maximum retries. Used as maximum for all retryable
- operations such as fetching of the root region from root region
- server, getting a cell's value, starting a row update, etc.
- Default: 10.
- </description>
- </property>
- <property>
- <name>hbase.client.scanner.caching</name>
- <value>1</value>
- <description>Number of rows that will be fetched when calling next
- on a scanner if it is not served from (local, client) memory. Higher
- caching values will enable faster scanners but will eat up more memory
- and some calls of next may take longer and longer times when the cache is empty.
- Do not set this value such that the time between invocations is greater
- than the scanner timeout; i.e. hbase.regionserver.lease.period
- </description>
- </property>
- <property>
- <name>hbase.client.keyvalue.maxsize</name>
- <value>10485760</value>
- <description>Specifies the combined maximum allowed size of a KeyValue
- instance. This is to set an upper boundary for a single entry saved in a
- storage file. Since they cannot be split it helps avoiding that a region
- cannot be split any further because the data is too large. It seems wise
- to set this to a fraction of the maximum region size. Setting it to zero
- or less disables the check.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.lease.period</name>
- <value>60000</value>
- <description>HRegion server lease period in milliseconds. Default is
- 60 seconds. Clients must report in within this period else they are
- considered dead.</description>
- </property>
- <property>
- <name>hbase.regionserver.handler.count</name>
- <value>10</value>
- <description>Count of RPC Server instances spun up on RegionServers
- Same property is used by the Master for count of master handlers.
- Default is 10.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.msginterval</name>
- <value>3000</value>
- <description>Interval between messages from the RegionServer to Master
- in milliseconds.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.flushlogentries</name>
- <value>1</value>
- <description>Sync the HLog to HDFS when it has accumulated this many
- entries. Default 1. Value is checked on every HLog.hflush
- </description>
- </property>
- <property>
- <name>hbase.regionserver.optionallogflushinterval</name>
- <value>1000</value>
- <description>Sync the HLog to the HDFS after this interval if it has not
- accumulated enough entries to trigger a sync. Default 1 second. Units:
- milliseconds.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.regionSplitLimit</name>
- <value>2147483647</value>
- <description>Limit for the number of regions after which no more region
- splitting should take place. This is not a hard limit for the number of
- regions but acts as a guideline for the regionserver to stop splitting after
- a certain limit. Default is set to MAX_INT; i.e. do not block splitting.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.logroll.period</name>
- <value>3600000</value>
- <description>Period at which we will roll the commit log regardless
- of how many edits it has.</description>
- </property>
- <property>
- <name>hbase.regionserver.hlog.reader.impl</name>
- <value>org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader</value>
- <description>The HLog file reader implementation.</description>
- </property>
- <property>
- <name>hbase.regionserver.hlog.writer.impl</name>
- <value>org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogWriter</value>
- <description>The HLog file writer implementation.</description>
- </property>
- <property>
- <name>hbase.regionserver.thread.splitcompactcheckfrequency</name>
- <value>20000</value>
- <description>How often a region server runs the split/compaction check.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.nbreservationblocks</name>
- <value>4</value>
- <description>The number of resevoir blocks of memory release on
- OOME so we can cleanup properly before server shutdown.
- </description>
- </property>
- <property>
- <name>hbase.zookeeper.dns.interface</name>
- <value>default</value>
- <description>The name of the Network Interface from which a ZooKeeper server
- should report its IP address.
- </description>
- </property>
- <property>
- <name>hbase.zookeeper.dns.nameserver</name>
- <value>default</value>
- <description>The host name or IP address of the name server (DNS)
- which a ZooKeeper server should use to determine the host name used by the
- master for communication and display purposes.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.dns.interface</name>
- <value>default</value>
- <description>The name of the Network Interface from which a region server
- should report its IP address.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.dns.nameserver</name>
- <value>default</value>
- <description>The host name or IP address of the name server (DNS)
- which a region server should use to determine the host name used by the
- master for communication and display purposes.
- </description>
- </property>
- <property>
- <name>hbase.master.dns.interface</name>
- <value>default</value>
- <description>The name of the Network Interface from which a master
- should report its IP address.
- </description>
- </property>
- <property>
- <name>hbase.master.dns.nameserver</name>
- <value>default</value>
- <description>The host name or IP address of the name server (DNS)
- which a master should use to determine the host name used
- for communication and display purposes.
- </description>
- </property>
- <property>
- <name>hbase.balancer.period
- </name>
- <value>300000</value>
- <description>Period at which the region balancer runs in the Master.
- </description>
- </property>
- <property>
- <name>hbase.master.logcleaner.ttl</name>
- <value>600000</value>
- <description>Maximum time a HLog can stay in the .oldlogdir directory,
- after which it will be cleaned by a Master thread.
- </description>
- </property>
- <property>
- <name>hbase.master.logcleaner.plugins</name>
- <value>org.apache.hadoop.hbase.master.TimeToLiveLogCleaner</value>
- <description>A comma-separated list of LogCleanerDelegate invoked by
- the LogsCleaner service. These WAL/HLog cleaners are called in order,
- so put the HLog cleaner that prunes the most HLog files in front. To
- implement your own LogCleanerDelegate, just put it in HBase's classpath
- and add the fully qualified class name here. Always add the above
- default log cleaners in the list.
- </description>
- </property>
- <property>
- <name>hbase.regionserver.global.memstore.upperLimit</name>
- <value>0.4</value>
- <description>Maximum size of all memstores in a region server before new
- updates are blocked and flushes are forced. Defaults to 40% of heap
- </description>
- </property>
- <property>
- <name>hbase.regionserver.global.memstore.lowerLimit</name>
- <value>0.35</value>
- <description>When memstores are being forced to flush to make room in
- memory, keep flushing until we hit this mark. Defaults to 35% of heap.
- This value equal to hbase.regionserver.global.memstore.upperLimit causes
- the minimum possible flushing to occur when updates are blocked due to
- memstore limiting.
- </description>
- </property>
- <property>
- <name>hbase.server.thread.wakefrequency</name>
- <value>10000</value>
- <description>Time to sleep in between searches for work (in milliseconds).
- Used as sleep interval by service threads such as log roller.
- </description>
- </property>
- <property>
- <name>hbase.hregion.memstore.flush.size</name>
- <value>67108864</value>
- <description>
- Memstore will be flushed to disk if size of the memstore
- exceeds this number of bytes. Value is checked by a thread that runs
- every hbase.server.thread.wakefrequency.
- </description>
- </property>
- <property>
- <name>hbase.hregion.preclose.flush.size</name>
- <value>5242880</value>
- <description>
- If the memstores in a region are this size or larger when we go
- to close, run a "pre-flush" to clear out memstores before we put up
- the region closed flag and take the region offline. On close,
- a flush is run under the close flag to empty memory. During
- this time the region is offline and we are not taking on any writes.
- If the memstore content is large, this flush could take a long time to
- complete. The preflush is meant to clean out the bulk of the memstore
- before putting up the close flag and taking the region offline so the
- flush that runs under the close flag has little to do.
- </description>
- </property>
- <property>
- <name>hbase.hregion.memstore.block.multiplier</name>
- <value>2</value>
- <description>
- Block updates if memstore has hbase.hregion.block.memstore
- time hbase.hregion.flush.size bytes. Useful preventing
- runaway memstore during spikes in update traffic. Without an
- upper-bound, memstore fills such that when it flushes the
- resultant flush files take a long time to compact or split, or
- worse, we OOME.
- </description>
- </property>
- <property>
- <name>hbase.hregion.max.filesize</name>
- <value>268435456</value>
- <description>
- Maximum HStoreFile size. If any one of a column families' HStoreFiles has
- grown to exceed this value, the hosting HRegion is split in two.
- Default: 256M.
- </description>
- </property>
- <property>
- <name>hbase.hstore.compactionThreshold</name>
- <value>3</value>
- <description>
- If more than this number of HStoreFiles in any one HStore
- (one HStoreFile is written per flush of memstore) then a compaction
- is run to rewrite all HStoreFiles files as one. Larger numbers
- put off compaction but when it runs, it takes longer to complete.
- </description>
- </property>
- <property>
- <name>hbase.hstore.blockingStoreFiles</name>
- <value>7</value>
- <description>
- If more than this number of StoreFiles in any one Store
- (one StoreFile is written per flush of MemStore) then updates are
- blocked for this HRegion until a compaction is completed, or
- until hbase.hstore.blockingWaitTime has been exceeded.
- </description>
- </property>
- <property>
- <name>hbase.hstore.blockingWaitTime</name>
- <value>90000</value>
- <description>
- The time an HRegion will block updates for after hitting the StoreFile
- limit defined by hbase.hstore.blockingStoreFiles.
- After this time has elapsed, the HRegion will stop blocking updates even
- if a compaction has not been completed. Default: 90 seconds.
- </description>
- </property>
- <property>
- <name>hbase.hstore.compaction.max</name>
- <value>10</value>
- <description>Max number of HStoreFiles to compact per 'minor' compaction.
- </description>
- </property>
- <property>
- <name>hbase.hregion.majorcompaction</name>
- <value>86400000</value>
- <description>The time (in miliseconds) between 'major' compactions of all
- HStoreFiles in a region. Default: 1 day.
- Set to 0 to disable automated major compactions.
- </description>
- </property>
- <property>
- <name>hbase.mapreduce.hfileoutputformat.blocksize</name>
- <value>65536</value>
- <description>The mapreduce HFileOutputFormat writes storefiles/hfiles.
- This is the minimum hfile blocksize to emit. Usually in hbase, writing
- hfiles, the blocksize is gotten from the table schema (HColumnDescriptor)
- but in the mapreduce outputformat context, we don't have access to the
- schema so get blocksize from Configuation. The smaller you make
- the blocksize, the bigger your index and the less you fetch on a
- random-access. Set the blocksize down if you have small cells and want
- faster random-access of individual cells.
- </description>
- </property>
- <property>
- <name>hfile.block.cache.size</name>
- <value>0.2</value>
- <description>
- Percentage of maximum heap (-Xmx setting) to allocate to block cache
- used by HFile/StoreFile. Default of 0.2 means allocate 20%.
- Set to 0 to disable.
- </description>
- </property>
- <property>
- <name>hbase.hash.type</name>
- <value>murmur</value>
- <description>The hashing algorithm for use in HashFunction. Two values are
- supported now: murmur (MurmurHash) and jenkins (JenkinsHash).
- Used by bloom filters.
- </description>
- </property>
- <property>
- <name>zookeeper.session.timeout</name>
- <value>180000</value>
- <description>ZooKeeper session timeout.
- HBase passes this to the zk quorum as suggested maximum time for a
- session. See http://hadoop.apache.org/zookeeper/docs/current/zookeeperProgrammers.html#ch_zkSessions
- "The client sends a requested timeout, the server responds with the
- timeout that it can give the client. "
- In milliseconds.
- </description>
- </property>
- <property>
- <name>zookeeper.znode.parent</name>
- <value>/hbase</value>
- <description>Root ZNode for HBase in ZooKeeper. All of HBase's ZooKeeper
- files that are configured with a relative path will go under this node.
- By default, all of HBase's ZooKeeper file path are configured with a
- relative path, so they will all go under this directory unless changed.
- </description>
- </property>
- <property>
- <name>zookeeper.znode.rootserver</name>
- <value>root-region-server</value>
- <description>Path to ZNode holding root region location. This is written by
- the master and read by clients and region servers. If a relative path is
- given, the parent folder will be ${zookeeper.znode.parent}. By default,
- this means the root location is stored at /hbase/root-region-server.
- </description>
- </property>
- <!--
- The following three properties are used together to create the list of
- host:peer_port:leader_port quorum servers for ZooKeeper.
- -->
- <property>
- <name>hbase.zookeeper.quorum</name>
- <value>localhost</value>
- <description>Comma separated list of servers in the ZooKeeper Quorum.
- For example, "host1.mydomain.com,host2.mydomain.com,host3.mydomain.com".
- By default this is set to localhost for local and pseudo-distributed modes
- of operation. For a fully-distributed setup, this should be set to a full
- list of ZooKeeper quorum servers. If HBASE_MANAGES_ZK is set in hbase-env.sh
- this is the list of servers which we will start/stop ZooKeeper on.
- </description>
- </property>
- <property>
- <name>hbase.zookeeper.peerport</name>
- <value>2888</value>
- <description>Port used by ZooKeeper peers to talk to each other.
- See http://hadoop.apache.org/zookeeper/docs/r3.1.1/zookeeperStarted.html#sc_RunningReplicatedZooKeeper
- for more information.
- </description>
- </property>
- <property>
- <name>hbase.zookeeper.leaderport</name>
- <value>3888</value>
- <description>Port used by ZooKeeper for leader election.
- See http://hadoop.apache.org/zookeeper/docs/r3.1.1/zookeeperStarted.html#sc_RunningReplicatedZooKeeper
- for more information.
- </description>
- </property>
- <!-- End of properties used to generate ZooKeeper host:port quorum list. -->
- <!--
- Beginning of properties that are directly mapped from ZooKeeper's zoo.cfg.
- All properties with an "hbase.zookeeper.property." prefix are converted for
- ZooKeeper's configuration. Hence, if you want to add an option from zoo.cfg,
- e.g. "initLimit=10" you would append the following to your configuration:
- <property>
- <name>hbase.zookeeper.property.initLimit</name>
- <value>10</value>
- </property>
- -->
- <property>
- <name>hbase.zookeeper.property.initLimit</name>
- <value>10</value>
- <description>Property from ZooKeeper's config zoo.cfg.
- The number of ticks that the initial synchronization phase can take.
- </description>
- </property>
- <property>
- <name>hbase.zookeeper.property.syncLimit</name>
- <value>5</value>
- <description>Property from ZooKeeper's config zoo.cfg.
- The number of ticks that can pass between sending a request and getting an
- acknowledgment.
- </description>
- </property>
- <property>
- <name>hbase.zookeeper.property.dataDir</name>
- <value>${hbase.tmp.dir}/zookeeper</value>
- <description>Property from ZooKeeper's config zoo.cfg.
- The directory where the snapshot is stored.
- </description>
- </property>
- <property>
- <name>hbase.zookeeper.property.clientPort</name>
- <value>2181</value>
- <description>Property from ZooKeeper's config zoo.cfg.
- The port at which the clients will connect.
- </description>
- </property>
- <property>
- <name>hbase.zookeeper.property.maxClientCnxns</name>
- <value>30</value>
- <description>Property from ZooKeeper's config zoo.cfg.
- Limit on number of concurrent connections (at the socket level) that a
- single client, identified by IP address, may make to a single member of
- the ZooKeeper ensemble. Set high to avoid zk connection issues running
- standalone and pseudo-distributed.
- </description>
- </property>
- <!-- End of properties that are directly mapped from ZooKeeper's zoo.cfg -->
- <property>
- <name>hbase.rest.port</name>
- <value>8080</value>
- <description>The port for the HBase REST server.</description>
- </property>
- <property>
- <name>hbase.rest.readonly</name>
- <value>false</value>
- <description>
- Defines the mode the REST server will be started in. Possible values are:
- false: All HTTP methods are permitted - GET/PUT/POST/DELETE.
- true: Only the GET method is permitted.
- </description>
- </property>
- </configuration></span>
- <span style="font-family:Microsoft YaHei;"><span style="color: rgb(51, 51, 51); font-size: 14px; line-height: 26px;">转自:</span><span style="color: rgb(51, 51, 51); font-size: 14px; line-height: 26px;">http://blog.csdn.net/macyang/article/details/6211141</span>
- </span>
除了这篇介绍hbase配置的文章之外,在推荐几篇其他的文章:
hbase参数配置及优化(http://blog.csdn.net/huoyunshen88/article/details/9169077)全文如下:
因官方Book Performance Tuning部分章节没有按配置项进行索引,不能达到快速查阅的效果。所以我以配置项驱动,重新整理了原文,并补充一些自己的理解,如有错误,欢迎指正。
配置优化
zookeeper.session.timeout
默认值:3分钟(180000ms)
说明:RegionServer与Zookeeper间的连接超时时间。当超时时间到后,ReigonServer会被Zookeeper从RS集群清单中移除,HMaster收到移除通知后,会对这台server负责的regions重新balance,让其他存活的RegionServer接管.
调优:
这个timeout决定了RegionServer是否能够及时的failover。设置成1分钟或更低,可以减少因等待超时而被延长的failover时间。
不过需要注意的是,对于一些Online应用,RegionServer从宕机到恢复时间本身就很短的(网络闪断,crash等故障,运维可快速介入),如果调低timeout时间,反而会得不偿失。因为当ReigonServer被正式从RS集群中移除时,HMaster就开始做balance了(让其他RS根据故障机器记录的WAL日志进行恢复)。当故障的RS在人工介入恢复后,这个balance动作是毫无意义的,反而会使负载不均匀,给RS带来更多负担。特别是那些固定分配regions的场景。
hbase.zookeeper.quorum
默认值:localhost
说明:hbase所依赖的zookeeper部署
调优:
部署的zookeeper越多,可靠性就越高,但是部署只能部署奇数个,主要为了便于选出leader。最好给每个zookeeper 1G的内存和独立的磁盘,可以确保高性能。hbase.zookeeper.property.dataDir可以修改zookeeper保存数据的路径。
hbase.regionserver.handler.count
默认值:10
说明:RegionServer的请求处理IO线程数。
调优:
这个参数的调优与内存息息相关。
较少的IO线程,适用于处理单次请求内存消耗较高的Big PUT场景(大容量单次PUT或设置了较大cache的scan,均属于Big PUT)或ReigonServer的内存比较紧张的场景。
较多的IO线程,适用于单次请求内存消耗低,TPS要求非常高的场景。设置该值的时候,以监控内存为主要参考。
这里需要注意的是如果server的region数量很少,大量的请求都落在一个region上,因快速充满memstore触发flush导致的读写锁会影响全局TPS,不是IO线程数越高越好。
压测时,开启Enabling RPC-level logging,可以同时监控每次请求的内存消耗和GC的状况,最后通过多次压测结果来合理调节IO线程数。
这里是一个案例?Hadoop and HBase Optimization for Read Intensive Search Applications,作者在SSD的机器上设置IO线程数为100,仅供参考。
hbase.hregion.max.filesize
默认值:256M
说明:在当前ReigonServer上单个Reigon的最大存储空间,单个Region超过该值时,这个Region会被自动split成更小的region。
调优:
小region对split和compaction友好,因为拆分region或compact小region里的storefile速度很快,内存占用低。缺点是split和compaction会很频繁。
特别是数量较多的小region不停地split, compaction,会导致集群响应时间波动很大,region数量太多不仅给管理上带来麻烦,甚至会引发一些Hbase的bug。
一般512以下的都算小region。
大region,则不太适合经常split和compaction,因为做一次compact和split会产生较长时间的停顿,对应用的读写性能冲击非常大。此外,大region意味着较大的storefile,compaction时对内存也是一个挑战。
当然,大region也有其用武之地。如果你的应用场景中,某个时间点的访问量较低,那么在此时做compact和split,既能顺利完成split和compaction,又能保证绝大多数时间平稳的读写性能。
既然split和compaction如此影响性能,有没有办法去掉?
compaction是无法避免的,split倒是可以从自动调整为手动。
只要通过将这个参数值调大到某个很难达到的值,比如100G,就可以间接禁用自动split(RegionServer不会对未到达100G的region做split)。
再配合RegionSplitter这个工具,在需要split时,手动split。
手动split在灵活性和稳定性上比起自动split要高很多,相反,管理成本增加不多,比较推荐online实时系统使用。
内存方面,小region在设置memstore的大小值上比较灵活,大region则过大过小都不行,过大会导致flush时app的IO wait增高,过小则因store file过多影响读性能。
hbase.regionserver.global.memstore.upperLimit/lowerLimit
默认值:0.4/0.35
upperlimit说明:hbase.hregion.memstore.flush.size 这个参数的作用是当单个Region内所有的memstore大小总和超过指定值时,flush该region的所有memstore。RegionServer的flush是通过将请求添加一个队列,模拟生产消费模式来异步处理的。那这里就有一个问题,当队列来不及消费,产生大量积压请求时,可能会导致内存陡增,最坏的情况是触发OOM。
这个参数的作用是防止内存占用过大,当ReigonServer内所有region的memstores所占用内存总和达到heap的40%时,HBase会强制block所有的更新并flush这些region以释放所有memstore占用的内存。
lowerLimit说明: 同upperLimit,只不过lowerLimit在所有region的memstores所占用内存达到Heap的35%时,不flush所有的memstore。它会找一个memstore内存占用最大的region,做个别flush,此时写更新还是会被block。lowerLimit算是一个在所有region强制flush导致性能降低前的补救措施。在日志中,表现为 “** Flush thread woke up with memory above low water.”
调优:这是一个Heap内存保护参数,默认值已经能适用大多数场景。
参数调整会影响读写,如果写的压力大导致经常超过这个阀值,则调小读缓存hfile.block.cache.size增大该阀值,或者Heap余量较多时,不修改读缓存大小。
如果在高压情况下,也没超过这个阀值,那么建议你适当调小这个阀值再做压测,确保触发次数不要太多,然后还有较多Heap余量的时候,调大hfile.block.cache.size提高读性能。
还有一种可能性是?hbase.hregion.memstore.flush.size保持不变,但RS维护了过多的region,要知道 region数量直接影响占用内存的大小。
hfile.block.cache.size
默认值:0.2
说明:storefile的读缓存占用Heap的大小百分比,0.2表示20%。该值直接影响数据读的性能。
调优:当然是越大越好,如果写比读少很多,开到0.4-0.5也没问题。如果读写较均衡,0.3左右。如果写比读多,果断默认吧。设置这个值的时候,你同时要参考?hbase.regionserver.global.memstore.upperLimit?,该值是memstore占heap的最大百分比,两个参数一个影响读,一个影响写。如果两值加起来超过80-90%,会有OOM的风险,谨慎设置。
hbase.hstore.blockingStoreFiles
默认值:7
说明:在flush时,当一个region中的Store(Coulmn Family)内有超过7个storefile时,则block所有的写请求进行compaction,以减少storefile数量。
调优:block写请求会严重影响当前regionServer的响应时间,但过多的storefile也会影响读性能。从实际应用来看,为了获取较平滑的响应时间,可将值设为无限大。如果能容忍响应时间出现较大的波峰波谷,那么默认或根据自身场景调整即可。
hbase.hregion.memstore.block.multiplier
默认值:2
说明:当一个region里的memstore占用内存大小超过hbase.hregion.memstore.flush.size两倍的大小时,block该region的所有请求,进行flush,释放内存。
虽然我们设置了region所占用的memstores总内存大小,比如64M,但想象一下,在最后63.9M的时候,我Put了一个200M的数据,此时memstore的大小会瞬间暴涨到超过预期的hbase.hregion.memstore.flush.size的几倍。这个参数的作用是当memstore的大小增至超过hbase.hregion.memstore.flush.size 2倍时,block所有请求,遏制风险进一步扩大。
调优: 这个参数的默认值还是比较靠谱的。如果你预估你的正常应用场景(不包括异常)不会出现突发写或写的量可控,那么保持默认值即可。如果正常情况下,你的写请求量就会经常暴长到正常的几倍,那么你应该调大这个倍数并调整其他参数值,比如hfile.block.cache.size和hbase.regionserver.global.memstore.upperLimit/lowerLimit,以预留更多内存,防止HBase server OOM。
hbase.hregion.memstore.mslab.enabled
默认值:true
说明:减少因内存碎片导致的Full GC,提高整体性能。
调优:详见 http://kenwublog.com/avoid-full-gc-in-hbase-using-arena-allocation
hbase.client.scanner.caching
默认值:1
说明:scanner调用next方法一次获取的数据条数
调优:少的RPC是提高hbase执行效率的一种方法,理论上一次性获取越多数据就会越少的RPC,也就越高效。但是内存是最大的障碍。设置这个值的时候要选择合适的大小,一面一次性获取过多数据占用过多内存,造成其他程序使用内存过少。或者造成程序超时等错误(这个超时与hbase.regionserver.lease.period相关)。
hbase.regionserver.lease.period
默认值:60000
说明:客户端租用HRegion server 期限,即超时阀值。
调优:
这个配合hbase.client.scanner.caching使用,如果内存够大,但是取出较多数据后计算过程较长,可能超过这个阈值,适当可设置较长的响应时间以防被认为宕机