[HDFS-7633] BlockPoolSliceScanner fails when Datanode has too many blocks

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Not A Problem
• Affects Version/s: 2.6.0
• Component/s: datanode
• Assignee: Walter Su
• Reporter: Walter Su
• Created: 16/Jan/15 07:47
• Updated: 28/Sep/15 18:47
• Resolved: 28/Sep/15 18:47

Description

issue:
When Total blocks of one of my DNs reaches 33554432, It refuses to accept more blocks, this is the ERROR.
2015-01-16 15:21:44,571 | ERROR | DataXceiver for client at /172.1.1.8:50490 [Receiving block BP-1976278848-172.1.1.2-1419846518085:blk_1221043436_147936990] | datasight-198:25009:DataXceiver error processing WRITE_BLOCK operation src: /172.1.1.8:50490 dst: /172.1.1.11:25009 | org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:250)
java.lang.IllegalArgumentException: n must be positive
at java.util.Random.nextInt(Random.java:300)
at org.apache.hadoop.hdfs.server.datanode.BlockPoolSliceScanner.getNewBlockScanTime(BlockPoolSliceScanner.java:263)
at org.apache.hadoop.hdfs.server.datanode.BlockPoolSliceScanner.addBlock(BlockPoolSliceScanner.java:276)
at org.apache.hadoop.hdfs.server.datanode.DataBlockScanner.addBlock(DataBlockScanner.java:193)
at org.apache.hadoop.hdfs.server.datanode.DataNode.closeBlock(DataNode.java:1733)
at org.apache.hadoop.hdfs.server.datanode.DataXceiver.writeBlock(DataXceiver.java:765)
at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.opWriteBlock(Receiver.java:124)
at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.processOp(Receiver.java:71)
at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:232)
at java.lang.Thread.run(Thread.java:745)

analysis:
in function org.apache.hadoop.hdfs.server.datanode.BlockPoolSliceScanner.getNewBlockScanTime()
when blockMap.size() is too big,
Math.max(blockMap.size(),1) * 600 is int type, and negtive
Math.max(blockMap.size(),1) * 600 * 1000L is long type, and negtive
(int)period is Integer.MIN_VALUE
Math.abs((int)period) is Integer.MIN_VALUE , which is negtive
DFSUtil.getRandom().nextInt(periodInt) will thows IllegalArgumentException

I use Java HotSpot (build 1.7.0_05-b05)

Issue Links

• is broken by: HDFS-7430 Rewrite the BlockScanner to use O(1) memory and use multiple threads