TestDU.testDU() throws assertionfailederror

["Edward J. Yoon" <ed...@udanax.org>]

Hi, community.

In my local computer (CentOS 5), TestDU.testDU() throws assertionfailederror.
What is the "4096 byte"?

Testsuite: org.apache.hadoop.fs.TestDU
Tests run: 1, Failures: 1, Errors: 0, Time elapsed: 5.143 sec

Testcase: testDU took 5.138 sec
       FAILED
expected:<32768> but was:<36864>
junit.framework.AssertionFailedError: expected:<32768> but was:<36864>
       at org.apache.hadoop.fs.TestDU.testDU(TestDU.java:77)

[root@udanax hadoop]# df -T
Filesystem    Type   1K-blocks      Used Available Use% Mounted on
/dev/sda1     ext3    52980472  11103380  39185808  23% /
none         tmpfs      516924         0    516924   0% /dev/shm

Thanks.
-- 
B. Regards,
Edward J. Yoon

Re: TestDU.testDU() throws assertionfailederror

[Konstantin Shvachko <sh...@yahoo-inc.com>]

Edward,

testDU() writes a 32K file to the local fs and then verifies whether the value reported by du
changes exactly to the amount written.
Although this is true for most block oriented file systems it might not be true for some.
I suspect that in your case the file is written to tmpfs, which is a memory fs and thus
creates an inode a directory entry and may be something else in memory (4K total) in addition
to the actual data. That is why du returns a different value and test fails.
Although TestDU is not universal we still want it to run in order to prevent bugs in DU on "real" file systems.

Thanks,
--Konstantin


Edward J. Yoon wrote:
> Hi, community.
> 
> In my local computer (CentOS 5), TestDU.testDU() throws assertionfailederror.
> What is the "4096 byte"?
> 
> Testsuite: org.apache.hadoop.fs.TestDU
> Tests run: 1, Failures: 1, Errors: 0, Time elapsed: 5.143 sec
> 
> Testcase: testDU took 5.138 sec
>        FAILED
> expected:<32768> but was:<36864>
> junit.framework.AssertionFailedError: expected:<32768> but was:<36864>
>        at org.apache.hadoop.fs.TestDU.testDU(TestDU.java:77)
> 
> [root@udanax hadoop]# df -T
> Filesystem    Type   1K-blocks      Used Available Use% Mounted on
> /dev/sda1     ext3    52980472  11103380  39185808  23% /
> none         tmpfs      516924         0    516924   0% /dev/shm
> 
> Thanks.