[HDFS-3488] BlockPoolSliceScanner#getNewBlockScanTime does not handle numbers > 31 bits properly

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Cannot Reproduce
• Assignee: Colin McCabe
• Reporter: Colin McCabe
• Created: 01/Jun/12 01:03
• Updated: 22/May/15 11:52
• Resolved: 22/May/15 11:52

Description

This code does not handle the case where period > 2**31 properly:

    long period = Math.min(scanPeriod, 
                           Math.max(blockMap.size(),1) * 600 * 1000L);
    int periodInt = Math.abs((int)period);
    return System.currentTimeMillis() - scanPeriod + 
        DFSUtil.getRandom().nextInt(periodInt);

So, for example, if period = 0x100000000, we'll map that to 0, and so forth.

Issue Links

• relates to: HDFS-2541 For a sufficiently large value of blocks, the DN Scanner may request a random number with a negative seed value.
• relates to: HDFS-7430 Rewrite the BlockScanner to use O(1) memory and use multiple threads