Question

At work we are using some pretty powerful machines: HP Z600 with dual xeon @2.5GHz, 8-16GB ram. Unfortunately due to ill-fitting company policies we are forced to use 32-bit XP, so I made a PAE ramdrive out of the unused 4GB RAM.

Now, the temporary files are on the ramdrive. I’ve also tried moving the whole project to the ramdrive, then to an SSD, but there was no noticeable improvement in hosted-mode startup or compilation times.

I’ve then run SysInternals’ Process Monitor to see if there are any bottlenecks that are not visible with task manager / hard-disk activity led, but I have not seen anything notable – except some buffer overflows which I don’t understand what they mean.


I can assume that performance for OOMPH startup and GWT compilation are tied so I’m using the compilation times as benchmarking between various changes.

I’ve activated and deactivated hyper-threading and turbo-boost in BIOS, but again saw no differences. Hyperthreading even seems to make everything slower, I can assume that context switching penalty is higher for 16 cores than for 8 cores. Turbo-boost does not seem to do anything, I can assume it only works under Win7, I have not succeeded in activating the driver. It should boost the core from 2.5Ghz to 2.8Ghz.

Deactivated indexing and timestamping on NTFS drives, changed the performance setting from foreground to background and back, used another instance of Eclipse – no changes.


For compilation I’ve tried specifying a different number of workers, larger memory and some other options. Everything above two workers increases compilation time.


Older HP machines (XW6600) seem to compile a bit faster, perhaps because of the 2.8GHz clock, but their hosted mode seems to start up slower.

To sum up, memory usage is at about 2.6GB, pagefile usage is zero, harddrive is not signaling much activity, CPU activity is <10% (single core at about 50-70%) but still the computer seems to do nothing for some time while compiling or launching OOMPH GWT.

Ok, so now that I’ve tried everything I knew and found on the Internet, is there anything else that I can try? Will switching to 64-bit Win7 improve much (this is due next year anyway)? Are there any hardware/software options that I can tweak?

L.E.: also ran RATT (tracer from MS) to see if there are any interrupts taking too long, but everything seems in order. Antivirus does not make a difference. Benchmarked another GWT project against my i7 mobile (2630q) and the i7 is about 70% faster, though it has about the same clock.

Answer 1

In most cases I’ve encountered the reason for slow compilation/hosted mode refresh is that application is written this way.

For compilation there are few things to watch out for:

• Don’t keep unused classes and modules in your classpath, remove them if possible because GWT is parsing them anyway at precompile stage
• whatch out for GWT-RPC type explosion, this is usually a cause of all problems
• Be really carefull with interface ContextWithLokup, always try to minimize the number of methods used in interface which extends ContextWithLookup
• Try to check out some other compilation options, like distributed compilation , soft permutations or multi-jvm compilation (run compiler with system property -Dgwt.jjs.permutationWorkerFactory=com.google.gwt.dev.ExternalPermutationWorkerFactory and -localWorkers to specify number of JVMs)

For hosted mode:

• Use lazy loading where it is possible. The greatest problem with hosted mode i saw, i that application is trying to initialize too many classes which aren’t even used on current screen, this can greatly speedup a hosted mode startup. Again, stuff like RPC type explosion affects hosted mode as well

That’s all I can advise. Stuff like ram disk can speed up stuff like -compileReport, since it can generate a huge number of files.