Hi Magnus:
Bug: https://bugs.openjdk.java.net/browse/JDK-8027584
While ccache can be used to speed up recompilations, there are also
several issues with ccache. Old versions does not work correctly for
the jdk (we try to detect that). It does not work well on other
platforms than Linux; on Windows it does not work at all. Nevertheless
is ccache enabled on Windows if it is installed, which it apparently
tends to be with Cygwin nowadays, requiring the use of
--disable-ccache to avoid compilation failure.
In many circumstances ccache also does not provide any performance
benefit. For instance, new compilations gets a performance hit. Only
recompilations benefits.
We had a case on a Linux system where ccache created a default cache
directory under the user's $HOME directory. Unfortunately $HOME was an
NFS mount to a home directory server on the other side of the country.
Even with the source and build output files on local disk, build
performance was (ahem) terrible until we sorted that out. Something to
watch out for if you decide to use ccache.
It is better to turn this upside down. This patch makes ccache
disabled by default, on all platforms. If you want ccache and are sure
you are in a situation that benefits from it, then you can enable it.
It also removes the output in configure hinting that ccache should be
used.
WebRev:
http://cr.openjdk.java.net/~ihse/JDK-8027584-disable-ccache-by-default/webrev.0
Looks good to me.
Tim
