[jira] [Commented] (KUDU-2094) GCC 7.1 complains about alignment of Counter

["Todd Lipcon (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KUDU-2094?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16122626#comment-16122626 ] 

Todd Lipcon commented on KUDU-2094:
-----------------------------------

can you paste the exact warning you're getting? I think this is because Counter's superclass Striped64 includes a 'Cell' member, which is marked with CACHELINE_ALIGNED. However, it should also be exactly size 64. Perhaps this gets messed up by being embedded in a non-POD class or somesuch, though.

> GCC 7.1 complains about alignment of Counter
> --------------------------------------------
>
>                 Key: KUDU-2094
>                 URL: https://issues.apache.org/jira/browse/KUDU-2094
>             Project: Kudu
>          Issue Type: Bug
>            Reporter: Tim Armstrong
>            Priority: Minor
>
> I found this when building the kudu/util subtree in Impala with gcc 7.1.
> In a few places, e.g. metrics.h, the compiler complains that the alignment required by Counter is less than the alignment guaranteed by new.
> {code}
>     m = new Counter(proto);
> {code}
> I worked around this by setting -faligned-new, which was added recently to GCC and is enabled by default with C++17. The setting ensures that new allocates memory with the alignment required by the data type.



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