YCSB Error with scan operation on mysql db

Question

I am trying to run a scan-only workload using YCSB client on MySQL database (a 10GB setup). I am using the following command to run the workload

./bin/ycsb run jdbc -P workloads/workloademod -p db.driver=com.mysql.jd bc.Driver -p db.url=jdbc:mysql://localhost:3306/ycsbtest -p db.user=username -p maxscanlength=100 -p recordcount=5000 -p operationcount=1000 -p maxexecutiontime=1800 > try_ycsb_emod

But I get java GC out of memory exception and the workload gets killed as follows:-

Loading workload...
Starting test.
Maximum execution time specified as: 1800 secs
Exception in thread "Thread-1" java.lang.OutOfMemoryError: Java heap space
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3380)
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3327)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3814)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:870)
        at com.mysql.jdbc.MysqlIO.nextRow(MysqlIO.java:1928)
        at com.mysql.jdbc.MysqlIO.readSingleRowSet(MysqlIO.java:3278)
        at com.mysql.jdbc.MysqlIO.getResultSet(MysqlIO.java:462)
        at com.mysql.jdbc.MysqlIO.readResultsForQueryOrUpdate(MysqlIO.java:2997)
        at com.mysql.jdbc.MysqlIO.readAllResults(MysqlIO.java:2245)
        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2638)
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2530)
        at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1907)
        at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2030)
        at com.yahoo.ycsb.db.JdbcDBClient.scan(JdbcDBClient.java:348)
        at com.yahoo.ycsb.DBWrapper.scan(DBWrapper.java:107)
        at com.yahoo.ycsb.workloads.CoreWorkload.doTransactionScan(CoreWorkload.java:605)
        at com.yahoo.ycsb.workloads.CoreWorkload.doTransaction(CoreWorkload.java:491)
        at com.yahoo.ycsb.ClientThread.run(Client.java:233)
Could not wait until max specified time, TerminatorThread interrupted.

I have tried increasing the java heap size for ycsb client by doing "export YCSB_HEAP_SIZE=8000" to make it 8G, still I get the same error.

I checked the mysql query that the ycsb client sends to mysql server and I don't see a reference/implication to the max_scan_length metric. Also, running this mysql query using a mysql client instead of the ycsb client works fine.

I am not sure what can I do to fix the same. Can someone help me out here?

Thanks, Rene

Answer 1

It's a bug with the jdbc implementation: https://github.com/brianfrankcooper/YCSB/issues/171