HBase Thrift2 CPU過高問題分析

目錄

目錄1

1.現象描述1

2.問題定位2

3.解決方案5

4.相關代碼5

1.現象描述

外界連接9090端口均超時，但telnet端口總是成功。使用top命令觀察，發現單個線程的CPU最高達99.99%，但並不總是99.9%，而是在波動。當遷走往該機器的流量後，能夠訪問成功，但仍然有超時，讀超時比寫超時多：

#./hbase_stress--hbase=110.13.136.207:9090--test=2--timeout=10

[2016-11-2710:15:21/771][139756154767104/31562][ERROR][hbase_stress.cpp:302]TransportException(thrift://110.13.136.207:9090):EAGAIN(timedout)

[2016-11-2710:15:31/775][139756154767104/31562][ERROR][hbase_stress.cpp:302]TransportException(thrift://110.13.136.207:9090):EAGAIN(timedout)

PIDUSERPRNIVIRTRESSHRS%CPU%MEMTIME+COMMAND

20727zhangsan20010.843g9.263g26344R99.926.41448:00java

20729zhangsan20010.843g9.263g26344R99.926.41448:00java

20730zhangsan20010.843g9.263g26344R99.926.41449:10java

20728zhangsan20010.843g9.263g26344R99.826.41448:00java

20693zhangsan20010.843g9.263g26344S0.026.40:00.00java

20727zhangsan20010.843g9.263g26344R75.526.41448:06java

20728zhangsan20010.843g9.263g26344R75.226.41448:06java

20729zhangsan20010.843g9.263g26344R75.226.41448:06java

20730zhangsan20010.843g9.263g26344R75.226.41449:15java

20716zhangsan20010.843g9.263g26344S24.926.493:48.75java

2.問題定位

使用ps命令找出CPU最多的線程，和top顯示的一致：

$ps-mp20693-oTHREAD,tid,time|sort-rn

zhangsan18.819----207301-00:11:23

zhangsan18.719----207291-00:10:13

zhangsan18.719----207281-00:10:13

zhangsan18.719----207271-00:10:13

zhangsan16.119-futex_--2073120:44:51

zhangsan5.219-futex_--2073206:46:39

然後借助jstack，發現為GC進程：

"Gangworker#0(ParallelCMSThreads)"os_prio=0tid=0x00007fb7200d4000nid=0x50f7runnable

"Gangworker#1(ParallelCMSThreads)"os_prio=0tid=0x00007fb7200d5800nid=0x50f8runnable

"Gangworker#2(ParallelCMSThreads)"os_prio=0tid=0x00007fb7200d7800nid=0x50f9runnable

"Gangworker#3(ParallelCMSThreads)"os_prio=0tid=0x00007fb7200d9000nid=0x50farunnable

使用jstat工具查看GC，情況很不樂觀，問題就是有GC引起的：

$jstat-gcutil206931000100

S0S1EOMCCSYGCYGCTFGCFGCTGCT

0.0099.67100.00100.0098.0894.4142199369.1322708434869.60135238.733

0.0099.67100.00100.0098.0894.4142199369.1322708434870.44835239.580

0.0099.67100.00100.0098.0894.4142199369.1322708434870.44835239.580

0.0099.67100.00100.0098.0894.4142199369.1322708434870.44835239.580

$jstat-gccapacity20693

NGCMNNGCMXNGCS0CS1CECOGCMNOGCMXOGCOCMCMNMCMXMCCCSMNCCSMXCCSCYGCFGC

191808.01107520.01107520.0110720.0110720.0886080.0383680.08094144.08094144.08094144.00.01077248.031584.00.01048576.03424.04219927156

$jstat-gcold20693

MCMUCCSCCCSUOCOUYGCFGCFGCTGCT

31584.030978.73424.03232.78094144.08094144.0421992717434964.34735333.479

$jstat-gcoldcapacity20693

OGCMNOGCMXOGCOCYGCFGCFGCTGCT

383680.08094144.08094144.08094144.0421992719234982.62335351.755

$jstat-gcnewcapacity20693

NGCMNNGCMXNGCS0CMXS0CS1CMXS1CECMXECYGCFGC

191808.01107520.01107520.0110720.0110720.0110720.0110720.0886080.0886080.04219927202

$jstat-gc20693

S0CS1CS0US1UECEUOCOUMCMUCCSCCCSUYGCYGCTFGCFGCTGCT

110720.0110720.00.0110395.9886080.0886080.08094144.08094144.031584.030978.73424.03232.742199369.1322720634996.53835365.671

$jstat-gcnew20693

S0CS1CS0US1UTTMTTDSSECEUYGCYGCT

110720.0110720.00.0110396.96655360.0886080.0886080.042199369.132

使用lsof顯示該進程的連接數不多，完全在安全范圍內，問題應當是有對象不能被回收。使用jmap查看內存詳情，先看堆的使用情況：

$jmap-heap20693

AttachingtoprocessID20693,pleasewait...

Debuggerattachedsuccessfully.

Servercompilerdetected.

JVMversionis25.77-b03

usingparallelthreadsinthenewgeneration.

usingthread-localobjectallocation.

ConcurrentMark-SweepGC

HeapConfiguration:

MinHeapFreeRatio=40

MaxHeapFreeRatio=70

MaxHeapSize=9422503936(8986.0MB)

NewSize=196411392(187.3125MB)

MaxNewSize=1134100480(1081.5625MB)

OldSize=392888320(374.6875MB)

NewRatio=2

SurvivorRatio=8

MetaspaceSize=21807104(20.796875MB)

CompressedClassSpaceSize=1073741824(1024.0MB)

MaxMetaspaceSize=17592186044415MB

G1HeapRegionSize=0(0.0MB)

HeapUsage:

NewGeneration(Eden+1SurvivorSpace):

capacity=1020723200(973.4375MB)

used=1020398064(973.1274261474609MB)

free=325136(0.3100738525390625MB)

99.96814650632022%used

EdenSpace:

capacity=907345920(865.3125MB)

used=907345920(865.3125MB)

free=0(0.0MB)

100.0%used

FromSpace:

capacity=113377280(108.125MB)

used=113052144(107.81492614746094MB)

free=325136(0.3100738525390625MB)

99.71322649476156%used

ToSpace:

capacity=113377280(108.125MB)

used=0(0.0MB)

free=113377280(108.125MB)

0.0%used

concurrentmark-sweepgeneration:

capacity=8288403456(7904.4375MB)

used=8288403424(7904.437469482422MB)

free=32(3.0517578125E-5MB)

99.9999996139184%used

10216internedStringsoccupying934640bytes.

進一步查看對象的情況：

$jmap-histo20693

num#instances#bytesclassname

----------------------------------------------

1:728352122518411456[B

2:498271471993085880java.util.TreeMap$Entry

3:12855993617087664java.util.TreeMap

4:4285217445662568org.apache.hadoop.hbase.client.ClientScanner

5:4285222377099536org.apache.hadoop.hbase.client.Scan

6:4284875377069000org.apache.hadoop.hbase.client.ScannerCallable

7:4285528342921344[Ljava.util.HashMap$Node;

8:4284880308511360org.apache.hadoop.hbase.client.ScannerCallableWithReplicas

9:8570671274261472java.util.LinkedList

10:4285579205707792java.util.HashMap

11:4285283205693584org.apache.hadoop.hbase.client.RpcRetryingCaller

12:3820914152836560org.apache.hadoop.hbase.filter.SingleColumnValueFilter

13:4291904137340928java.util.concurrent.ConcurrentHashMap$Node

14:8570636137130176java.util.TreeMap$EntrySet

15:4285278137128896org.apache.hadoop.hbase.io.TimeRange

16:8570479137127664java.util.concurrent.atomic.AtomicBoolean

17:289140992525088org.apache.hadoop.hbase.NoTagsKeyValue

18:428654068584640java.lang.Integer

19:428529868564768java.util.TreeMap$KeySet

20:428527568564400java.util.TreeSet

21:428500668560096java.util.HashSet

22:428485168557616java.util.HashMap$KeySet

23:317611850817888org.apache.hadoop.hbase.filter.BinaryComparator

24:10933607600[Ljava.util.concurrent.ConcurrentHashMap$Node;

25:41877518479112[Lorg.apache.hadoop.hbase.Cell;

26:67144317693224[C

27:41878116751240org.apache.hadoop.hbase.client.Result

28:66973916073736java.lang.String

29:64479615475104org.apache.hadoop.hbase.filter.SubstringComparator

30:41913410059216java.util.LinkedList$Node

為使系統能夠正常工作，先實施治標不治本的方案：監控GC，定時重啟HBaseThrift2進程，然後再找出根本原因達到治本的目的。

從上面jmap的輸出來看，猜測是不是因為額scanner沒有被關閉導致的。而scanner沒有被關閉的原因有兩個：一是客戶端程序問題沒有關閉，也就是有內存洩漏了，二是客戶端程序異常導致沒機會關閉。

查看客戶端源代碼，確實存在openScanner的異常時未關閉。另外客戶端被kill掉或斷電等，也會導致無法釋放，這一點是HBaseThrift2得解決的問題。

3.解決方案

針對前面分析出的問題分別加以解決：

1)客戶端保證scanner全部釋放；

2)HBaseThrift2增加自動釋放長時間未操作的scanner；

3)另外也可以使用getScannerResults替代getScannerRows來規避此問題。

補丁：

https://issues.apache.org/jira/browse/HBASE-17182。

4.相關代碼

privatefinalMap<Integer,ResultScanner>scannerMap

=newConcurrentHashMap<Integer,ResultScanner>();

@Override

publicintopenScanner(ByteBuffertable,TScanscan)throwsTIOError,TException{

Tablehtable=getTable(table);

ResultScannerresultScanner=null;

try{

resultScanner=htable.getScanner(scanFromThrift(scan));

}catch(IOExceptione){

throwgetTIOError(e);

}finally{

closeTable(htable);

}

//將scanner放入到scannerMap中，

//如果客戶端沒有調用closeScanner，則導致該scanner洩漏，GC無法回收改部分內存

returnaddScanner(resultScanner);

}

/**

*AssignsauniqueIDtothescannerandaddsthemappingtoaninternalHashMap.

*@paramscannertoadd

*@returnIdforthisScanner

*/

privateintaddScanner(ResultScannerscanner){

intid=nextScannerId.getAndIncrement();

scannerMap.put(id,scanner);//將scanner放入到scannerMap中

returnid;

}

/**

*ReturnstheScannerassociatedwiththespecifiedId.

*@paramidoftheScannertoget

*@returnaScanner,ornulliftheIdisinvalid

*/

privateResultScannergetScanner(intid){

returnscannerMap.get(id);

}

@Override

publicvoidcloseScanner(intscannerId)throwsTIOError,TIllegalArgument,TException{

LOG.debug("scannerClose:id="+scannerId);

ResultScannerscanner=getScanner(scannerId);

if(scanner==null){

Stringmessage="scannerIDisinvalid";

LOG.warn(message);

TIllegalArgumentex=newTIllegalArgument();

ex.setMessage("InvalidscannerId");

throwex;

}

scanner.close();//關閉scanner

removeScanner(scannerId);//從scannerMap中移除scanner

}

/**

*RemovesthescannerassociatedwiththespecifiedIDfromtheinternalHashMap.

*@paramidoftheScannertoremove

*@returntheremovedScanner,or<code>null</code>iftheIdisinvalid

*/

protectedResultScannerremoveScanner(intid){

returnscannerMap.remove(id);//從scannerMap中移除scanner

}