[Rake-devel] timestamp checking is slow?
ittay.dror at gmail.com
Wed Jul 23 05:31:14 EDT 2008
I applied your change and it sped up the execution by 0.1s :-(.
I then just added a 'return Rake::EARLY' at the start of #timestamp.
This also didn't improve time. So it must be something with the rake
code that calls the timestamp method.
Mark Watson wrote:
> I ran into a similar issue, the way i got around it was by caching the
> timestamp the first time File.mtime is called. This brings about its
> own problems because you don't necessarily know that the file won't be
> modified outside the file task. If you have a task that generates
> several files the cached timestamps won't be updated.
> I tried using Windows API directly instead of File.mtime but this
> wasn't much faster. I didn't get a chance to look into what make is
> doing, but i suspect it is caching the timestamps too. Make does
> allow you to specify several files as the output of one task, possibly
> as a way around the problems with caching the timestamp.
> # File task with timestamp speedup. The regular file task will query
> # the File.mtime for every task that depends on this file. Typically
> # when compiling c/c++ some header files are included very often, and
> # if a a regular file task is used to represent header files then the
> # File.mtime function will be called each time a source file depends
> # on the header. By caching the timestamp we insure that this
> # operation occurs only once for each header file. On typical c/c++
> # projects where most files depend on a core set of headers, a ~3x
> # speedup on rake startup time can be expected with this patch.
> # WARNING: Caching the timestamp may cause problems if the file is
> # generated/updated by another task as a side effect.
> class Rake::FastFileTask < Rake::FileTask
> # Time stamp for file task.
> def timestamp
> # Cache the timestamp since it is accessed often
> if instance_variable_defined?(:@timestamp)
> # exist? and mtime can be done together with one call to File.stat, but
> # for some reason this takes longer on Windows. Ruby is probably making
> # several Win32 calls. Opimization would be to call GetFileAttributesEx()
> # directly. Using Win32API module this is slightly faster, making the
> # call via a c extension would probably be faster again.
> if File.exist?(name)
> @timestamp = File.mtime(name.to_s)
> # Update the time stamp when the task is executed
> enhance do
> @timestamp = Time.now
> # Build me!
> 2008/7/22 Ittay Dror <ittay.dror at gmail.com>:
>> I'm using Rake (actually Buildr) to compile C++ files. As part of that I'm
>> loading dependencies on header files. The total amount of dependencies is
>> 869 on 142 obj files.
>> The issue I'm seeing is that it takes a lot of time for Rake to timestamp
>> these files to reach a conclusion that it has nothing to do. Compared to
>> make that takes 0.7 seconds to run, Rake takes 3 seconds. If I remove the
>> creation of the dependencies (but still leave the loading and parsing of the
>> files) rake takes 1 second.
>> I understand that 2 seconds seem like not a long time, but the project I'm
>> working on has over 1000 of source files, so I expect the time to be much
>> larger. Do you think anything can be done to make Rake closer to make? note
>> that without the timestamp checking, the rest of the work doesn't amount to
>> a lot of overhead, so I am hoping it is not the dynamic nature of Ruby that
>> is the cause of the problem (but maybe poor implementation of
>> Thank you,
>> Ittay Dror <ittay.dror at gmail.com>
>> Rake-devel mailing list
>> Rake-devel at rubyforge.org
> Rake-devel mailing list
> Rake-devel at rubyforge.org
Ittay Dror <ittay.dror at gmail.com>
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Rake-devel