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From "Simon Zhou (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-13397) Return value of CountDownLatch.await() not being checked
Date Fri, 31 Mar 2017 22:17:41 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-13397?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Simon Zhou updated CASSANDRA-13397:
-----------------------------------
    Description: 
While looking into repair code, I realize that we should check return value of CountDownLatch.await().
Most of the places that we don't check the return value, nothing bad would happen due to other
protection. However, ActiveRepairService#prepareForRepair should have the check. Code to reproduce:
{code}
    public static void testLatch() throws InterruptedException {
        CountDownLatch latch = new CountDownLatch(2);
        latch.countDown();

        new Thread(() -> {
            try {
                Thread.sleep(1200);
            } catch (InterruptedException e) {
                System.err.println("interrupted");
            }
            latch.countDown();
            System.out.println("counted down");
        }).start();


        latch.await(1, TimeUnit.SECONDS);
        if (latch.getCount() > 0) {
            System.err.println("failed");
        } else {
            System.out.println("success");
        }
    }
{code}

  was:
While looking into repair code, I realize that we should check return value of CountDownLatch.await().
However, there are some places we don't check and some of them may cause bad consequent behavior,
like in ActiveRepairService#prepareForRepair and StorageProxy#describeSchemaVersions. I haven't
checked the original version that has this bug but at least StorageProxy#describeSchemaVersions
has the bug starting from 2010. Code to reproduce:
{code}
    public static void testLatch() throws InterruptedException {
        CountDownLatch latch = new CountDownLatch(2);
        latch.countDown();

        new Thread(() -> {
            try {
                Thread.sleep(1200);
            } catch (InterruptedException e) {
                System.err.println("interrupted");
            }
            latch.countDown();
            System.out.println("counted down");
        }).start();


        latch.await(1, TimeUnit.SECONDS);
        if (latch.getCount() > 0) {
            System.err.println("failed");
        } else {
            System.out.println("success");
        }
    }
{code}


> Return value of CountDownLatch.await() not being checked
> --------------------------------------------------------
>
>                 Key: CASSANDRA-13397
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13397
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Simon Zhou
>            Assignee: Simon Zhou
>
> While looking into repair code, I realize that we should check return value of CountDownLatch.await().
Most of the places that we don't check the return value, nothing bad would happen due to other
protection. However, ActiveRepairService#prepareForRepair should have the check. Code to reproduce:
> {code}
>     public static void testLatch() throws InterruptedException {
>         CountDownLatch latch = new CountDownLatch(2);
>         latch.countDown();
>         new Thread(() -> {
>             try {
>                 Thread.sleep(1200);
>             } catch (InterruptedException e) {
>                 System.err.println("interrupted");
>             }
>             latch.countDown();
>             System.out.println("counted down");
>         }).start();
>         latch.await(1, TimeUnit.SECONDS);
>         if (latch.getCount() > 0) {
>             System.err.println("failed");
>         } else {
>             System.out.println("success");
>         }
>     }
> {code}



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