我应该为“ com.datastax.driver.core.exceptions.ReadTimeoutException”做什么？

Question

I put almost 190 million records in Cassandra(2.1.11) cluster with 3 nodes, and the replication factor is 1 , then I write client application to count the all records using datastax's Java Driver , the snippet code as follows:

Statement stmt = new SimpleStatement("select * from test" );

System.out.println("starting to read records ");
stmt.setFetchSize(10000);
ResultSet rs = session.execute(stmt);

//System.out.println("rs.size " + rs.all().size());
long cntRecords = 0;

for(Row row : rs){
    cntRecords++;

    if(cntRecords % 10000000 == 0){
        System.out.println("the " + cntRecords/10000000 + " X 10 millions of records");
    }
}

After the above variable cntRecords is more than 30 millions, I always get the exception:

Exception in thread "main" com.datastax.driver.core.exceptions.ReadTimeoutException: 
Cassandra timeout during read query at consistency ONE (1 responses were required but only 
0 replica responded)

I got several results in google and changed the settings about heap and GC, the following is my relative settings:

-XX:InitialHeapSize=17179869184 
-XX:MaxHeapSize=17179869184 
-XX:MaxNewSize=12884901888 
-XX:MaxTenuringThreshold=1 
-XX:NewSize=12884901888 
-XX:+UseCMSInitiatingOccupancyOnly 
-XX:+UseCompressedOops 
-XX:+UseConcMarkSweepGC 
-XX:+UseCondCardMark 
-XX:+UseGCLogFileRotation 
-XX:+UseParNewGC 
-XX:+UseTLAB 
-XX:+UseThreadPriorities
-XX:+CMSClassUnloadingEnabled 

and I used GCViewer to analysis the gc log file and the througputs are 99.95%, 98.15% and 95.75%.

UPDATED BEGIN: And I used jstat to monitor one of the three nodes and found that when the S1 's value changed into 100.00 I will get the above error quickly:

/usr/java/jdk1.7.0_80/bin/jstat -gcutil 8862 1000 
S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT   
0.00 100.00  28.57  36.29  74.66     55   14.612     2    0.164   14.776

And once S1 changed into 100.00 , S1 no longer will decrease, I don't know this is relative to the error? Or what property in cassandra.yaml or cassandra-env.sh I should set for this?

What should I do for finishing the task to count the all records? Thanks in advance!

ATTACH: the following is other options:

-XX:+CMSEdenChunksRecordAlways 
-XX:CMSInitiatingOccupancyFraction=75 
-XX:+CMSParallelInitialMarkEnabled 
-XX:+CMSParallelRemarkEnabled 
-XX:CMSWaitDuration=10000 
-XX:CompileCommandFile=bin/../conf/hotspot_compiler 
-XX:GCLogFileSize=94371840 
-XX:+HeapDumpOnOutOfMemoryError 
-XX:NumberOfGCLogFiles=90 
-XX:OldPLABSize=16 
-XX:PrintFLSStatistics=1 
-XX:+PrintGC 
-XX:+PrintGCApplicationStoppedTime 
-XX:+PrintGCDateStamps 
-XX:+PrintGCDetails 
-XX:+PrintGCTimeStamps 
-XX:+PrintHeapAtGC 
-XX:+PrintPromotionFailure 
-XX:+PrintTenuringDistribution 
-XX:StringTableSize=1000003 
-XX:SurvivorRatio=8 
-XX:ThreadPriorityPolicy=42 
-XX:ThreadStackSize=256 

Answer 1

Examine why you need to know the number of rows. Does your application really need to know this? If it can survive with "just" a good approximation, then create a counter and increment it as you load your data.

http://docs.datastax.com/en/cql/3.1/cql/cql_using/use_counter_t.html

Things you can try:

• Select a single column instead of * . This might reduce by GC pressure and network consumption. Preferably pick a column that has a small number of bytes and is part of the primary key: select column1 from test
• Add a short pause after every 1M records. Have your loop pause for 500ms or so every 1M records. This may give the nodes a quick breather to take care of things like GC
• Edit cassandra.yaml on your nodes and increase range_request_timeout_in_ms and read_request_timeout_in_ms
• Figure out the token ranges assigned to each node and issue a separate query for each token range. Add the counts from each query. This takes advantage of the token-aware driver to issue each "token range" query directly to the node that can answer it. See this blog article for a full description with sample code.