Ccache hangs while compiling and cache size is exaggerated

[Volodymyr Kostyrko]

02.01.2011 16:01, Anonymous wrote:
>> I'm using ccache 3.1.3, and it often hangs while compiling.
>
> What its waiting channel? Hit ^T when it hangs or run under ktrace(1).

Not just every compilation attempt triggers it. Chances are closer to 100/1.

>> Every time this happens, the cache size from $ ccache -s also becomes
>> ridiculously large (larger than the actual cache size).
>>
>> $ ccache -s
>> [...]
>> cache size    6.9 Gbytes
>
>> The filesystem says it's only 2.9 GB.
>
> How did you measure it? du(1) with `-A' option?
> For example, compression can make difference
>
>    $ df ~/.ccache
>    Filesystem     Size    Used   Avail Capacity  Mounted on
>    /.../.ccache    49G    666M     48G     1%    ~/.ccache
>
>    $ du -hs ~/.ccache
>    666M    ~/.ccache
>
>    $ du -Ahs ~/.ccache
>    912M    ~/.ccache

I'd clarify this one. ccache reports size of cache +4G per damaged 
subdir. If damaged subdir would be removed ccache reports normal size of 
cache again.

>> I can reproduce this, but I don't know what is causing this.

This gives high IO. When ccache thinks cache is full it tries to purge 
it, yet purge does nothing. But this means walking all subdir per each 
compilation.

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