We REALLY nead a NON-PCH build in JPRT NOW! (original) (raw)

Stefan Karlsson stefan.karlsson at oracle.com
Fri Apr 3 06:39:29 UTC 2015

On 2015-04-03 03:04, David Holmes wrote:

On 3/04/2015 2:06 AM, Volker Simonis wrote:

Hi,

while precompiled headers (PCH) are a nice and effective way of improving hotspot build times this feature also drastically increases IIUC PCH benefits incremental build times, not clean builds. It's useful for developer builds but not JPRT builds (or any official build).

I don't think this is the case. Usually incremental builds with PCH force you to "unnecessarily" recompile more files than you really have to. If I know that I'm doing a lot of incremental changes to header files, I usually turn off PCH.

StefanK

the risk of introducing missing dependencies into the source base. This is especially annoying on platforms where precompield headers aren't available at all.

In the last two weeks we had two cases [1,2] of such missing dependencies which haven't been caught by JPRT because JPRT uses the default platform settings and thus always uses PCHs on all platforms where they are supported. I want to strongly advocate for a change in the JPRT configurations such that at least on one Windows and one Linux platform the automatic pre-integration builds are done with "--with-debug-level=[slow/fast]debug --disable-precompiled-headers". One of the main areas where PCH hides problems is with the minimal VM, unfortunately the only builds that build the minimal VM are the embedded builds. Arguably we could add the minimal VM to a linux x86 build but we need to look at overall build times etc before making that the default. David This simple change which comes at the minor cost of a few CPU-cycles will save a big amount of (hopfully) much more precious developer cycles and at the same time considerably improve the code quality. Notice that I intentionally ask for a *debug build without PCHs because debug builds exercise much more source code and are specifically prone to missing include dependency errors. As this change can only be decided upon and implemented inside Oracle I hereby kindly ask for an appropriate sponsor. Thank you and best regards, Volker [1] Introduced by: https://bugs.openjdk.java.net/browse/JDK-8075416 Fixed by: https://bugs.openjdk.java.net/browse/JDK-8075735 [2] Introduced by: https://bugs.openjdk.java.net/browse/JDK-8076314 Fix proposed: http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2015-April/012659.html

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