hbase的优化的一点经验，一直没做这个笔记，是因为hbase自身也有设计缺陷，所以有些配置不能说优化，只能说因为hbase自身缺陷可以将就着用，不说废话了，以下就是优化的一点笔记
(split是因为hfile过多，进行split，split之后进行compact
可以可能要有人喷了，hfile多了应该compact才对啦。贴出0.98.1的代码，大致逻辑是region没有block的compact（优先级大于等于1的），则进行split)
private boolean flushRegion(final FlushRegionEntry fqe) {
HRegion region = fqe.region;
if (!region.getRegionInfo().isMetaRegion() &&
isTooManyStoreFiles(region)) {//这个函数使用了参数
if (fqe.isMaximumWait(this.blockingWaitTime)) {
LOG.info("Waited " + (System.currentTimeMillis() - fqe.createTime) +
"ms on a compaction to clean up 'too many store files'; waited " +
"long enough... proceeding with flush of " +
region.getRegionNameAsString());
} else {
// If this is first time we've been put off, then emit a log message.
if (fqe.getRequeueCount() <= 0) {
// Note: We don't impose blockingStoreFiles constraint on meta regions
LOG.warn("Region " + region.getRegionNameAsString() + " has too many " +
"store files; delaying flush up to " + this.blockingWaitTime + "ms");
if (!this.server.compactSplitThread.requestSplit(region)) {//这里是关键的逻辑，逻辑是region没有block的compact（优先级大于等于1的），则进行split；否则进行compact
try {
this.server.compactSplitThread.requestSystemCompaction(
region, Thread.currentThread().getName());
} catch (IOException e) {
LOG.error(
"Cache flush failed for region " + Bytes.toStringBinary(region.getRegionName()),
RemoteExceptionHandler.checkIOException(e));
}
}
}
// Put back on the queue. Have it come back out of the queue
// after a delay of this.blockingWaitTime / 100 ms.
this.flushQueue.add(fqe.requeue(this.blockingWaitTime / 100));
// Tell a lie, it's not flushed but it's ok
return true;
}
}
return flushRegion(region, false);
}
hbase.hstore.blockingStoreFiles hfile数量上限，如果超过，则进行阻塞写，进行split | compact
hbase.hstore.blockingWaitTime 阻塞写的时间上限 ，到时间没进行split或compact（就是没锁上，则继续）
最大region 500G，禁止常规的split情况
<property>
<name>hbase.hregion.max.filesize</name>
<value>536870912000</value>
</property>
一个store中30个hfile的上限
<property>
<name>hbase.hstore.blockingStoreFiles</name>
<value>30</value>
</property>
一分半的写的阻塞上限
<property>
<name>hbase.hstore.blockingWaitTime</name>
<value>90000</value>
</property>
hbase.regionserver.regionSplitLimit region包含的最大region数, split需要检查现有region不大于这个
compact Priority逻辑
初始化为int.minvalue,user为1，被block>1
-----------------------------------------------
DEBUG [LruStats #0] hfile.LruBlockCache: Total=11.78 GB, free=1.01 GB, max=12.79 GB,
memcache设置256
memcache使用mslb
使用mslb
<property>
<name>hbase.hregion.memstore.mslab.enabled</name>
<value>true</value>
</property>
memcash的flush的条件256M
<property>
<name>hbase.hregion.memstore.flush.size</name>
<value>268435456</value>
</property>
安全检查memstore使用region_heap的百分比 ， 强制flush
</property>
base.regionserver.global.memstore.lowerLimit
<property>
<name>hbase.regionserver.global.memstore.lowerLimit</name>
<value>0.36</value>
<description>
一个RS中所有的memstore的总容量超过堆的该百分比限制后，将被强制flush到磁盘。
Maximum size of all memstores in a region server before flushes are forced. Defaults to 35% of heap. 这个值与
hbase.regionserver.global.memstore.upperLimit相等，以减小由于到达该值触发flush的几率，因为这种flush会block写请求
</description>
</property>
安全检查memstore使用region_heap的百分比 ， 强制flush，并阻塞写请求
<property>
<name>hbase.regionserver.global.memstore.upperLimit</name>
<value>0.4</value>
<description>
一个region中所有memstore的总大小超过堆的该百分比限制时，会发生强制flush，并block更新请求。
默认是堆大小的40%。更新会被阻塞，并发生强制flush，直到所有memstore的大小达到
hbase.regionserver.global.memstore.lowerLimit的限制。
</description>
</property>
达到flushsize指定倍数时，会强制flush，并阻塞请求
<property>
<name>hbase.hregion.memstore.block.multiplier</name>
<value>2</value>
<description>
当一个region的memstore达到hbase.hregion.memstore.block.multiplier * hbase.hregion.flush.size的指定倍数时，阻塞写请求。
这是一个避免在写请求高峰时期避免memstore耗尽的有效设置。如果没有上限限制，memstore被填满后发生flush时，
会消耗大量的时间来处理合并和分割，甚至导致OOM。
</description>
</property>
----------------------------------------------------
gc的问题
3.5分钟挂掉
11 分钟
（70）提前gc，减少每个gc耗时
hbase-env.sh中
export HBASE_REGIONSERVER_OPTS="-Xmx16g -Xms16g -Xmn128m -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=70 -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -Xloggc:$HBASE_HOME/logs/gc-hbase.log"
----------------------------------------------------
compact时间是否过长？？
compact的时候gc过长
2015-02-25 11:54:50,670 WARN [regionserver60020.periodicFlusher] util.Sleeper: We slept 565427ms instead of 10000ms, this is likely due to a long garbage collecting pause and it's usually bad, se
e http://hbase.apache.org/book.html#trouble.rs.runtime.zkexpired
2015-02-25 11:54:50,670 WARN [DataStreamer for file /hbase/WALs/host64,60020,1422073827259/host64%2C60020%2C1422073827259.1424835178059 block BP-1540478979-192.168.5.117-1409220943611:blk_1097821
214_24084365] hdfs.DFSClient: Error Recovery for block BP-1540478979-192.168.5.117-1409220943611:blk_1097821214_24084365 in pipeline 192.168.5.64:50010, 192.168.5.95:50010: bad datanode 192.168.5.
64:50010
2015-02-25 11:54:50,670 WARN [regionserver60020.compactionChecker] util.Sleeper: We slept 565427ms instead of 10000ms, this is likely due to a long garbage collecting pause and it's usually bad,
see http://hbase.apache.org/book.html#trouble.rs.runtime.zkexpired
2015-02-25 11:54:50,670 INFO [regionserver60020-SendThread(host141:42181)] zookeeper.ClientCnxn: Client session timed out, have not heard from server in 577669ms for sessionid 0x44add78c8664fdb,
closing socket connection and attempting reconnect
转为手动compact，需要逐步手动compact
<property>
<name>hbase.hregion.majorcompaction</name>
<value>0</value>
</property>
------------------------------------------------------
regionserver里的handler数量 50
<property>
<name>hbase.regionserver.handler.count</name>
<value>50</value>
<source>hbase-site.xml</source>
</property>
--------------------------------------------------
wal大小，影响memcash flush
当前hbase.regionserver.hlog.blocksize * hbase.regionserver.maxlogs 128*32=4G
但是hbase.regionserver.global.memstore.lowerLimit * HBASE_HEAPSIZE 0.38*32=12.16G
hbase.regionserver.global.memstore.upperLimit * HBASE_HEAPSIZE 0.4*32=12.8
注意：确保hbase.regionserver.hlog.blocksize * hbase.regionserver.maxlogs 比hbase.regionserver.global.memstore.lowerLimit * HBASE_HEAPSIZE的值只高那么一点点。.
改为
<property>
<name>hbase.regionserver.maxlogs</name>
<value>104</value>
</property>
<property>
<name>hbase.regionserver.global.memstore.lowerLimit</name>
<value>0.36</value>
</property>
128*105=13G
0.36*32=11.52G
0.4*32=12.8G
原则是让memflush不阻塞，禁止因为wal触发的flush，wal会进行多region flush，并且阻塞，这是最坏的情况
---------------------------------------------------
blockcache是读取时使用内存
<property>
<name>hfile.block.cache.size</name>
<value>0.4</value>
</property>
----------------------------------------------------
超时时间待验证，设置或过长
<property>
<name>hbase.rowlock.wait.duration</name>
<value>90000</value>
<description>
每次获取行锁的超时时间，默认为30s
</description>
</property>
<property>
<name>hbase.regionserver.lease.period</name>
<value>180000</value>
<description>
客户端每次获得rs一次socket时间
</description>
</property>
<property>
<name>hbase.rpc.timeout</name>
<value>180000</value>
<description>
rpc超时时间
</description>
</property>
<property>
<name>hbase.client.scanner.timeout.period</name>
<value>180000</value>
<description>
客户端每次scan|get的超时时间
</description>
</property>
<property>
<name>hbase.client.scanner.caching</name>
<value>100</value>
<description>
客户端每次scan的一个next，获得多少行，默认1
</description>
</property>
