[Scons-users] Intermittent Install() failure

Hill, Steve (FP COM) Steve.Hill at cobham.com
Tue Jul 19 04:02:25 EDT 2016

Thanks William.


I’ve checked the dependency tree and, as far as I can tell, it looks OK.

We do have custom scanners – using env.Scanner(_scan_domain_header) – but not for the files that are affected.

As far as I can see, the fix for that Python bug never made it into 2.6.x but it appears always to result in a “No child processes” OSError so I don’t believe that is what I am seeing.


Note that I have (temporarily) changed the decider below to simply return True (without doing anything with the file) and I still see the issue so the decider doesn’t seem to be relevant to the issue.


Does anyone have any more ideas? This is becoming a major issue for our automated builds…






I of course should have asked the obvious question, do you know if you dependency tree has missing dependencies? This tends to be a common issue.




On Fri, Jul 15, 2016 at 5:14 PM, William Blevins <wblevins001 at gmail.com> wrote:


I'm not aware of any specific issue with install, but there are some possible issues that I am aware:

1.	If you have custom scanners, make sure they implement from SCons.Scanner.Current and not SCons.Scanner.Base; otherwise, you might have concurrent file access between implicit scanning operations and other processes.
2.	There was a big subprocess bug in python 2.6 that carried through several other major versions: https://bugs.python.org/issue1731717. I would check to see that your version of 2.6 contains the patch for this issue.




On Fri, Jul 15, 2016 at 9:30 AM, Hill, Steve (FP COM) <Steve.Hill at cobham.com> wrote:

	I’m having a problem where, with parallel builds (most people use 8, 12 or 16 threads), we occasionally get failures like the following:


	F:\<directory path>\hw_cfgs\1Server_1TM_6C66_2U.cfg: The process cannot access the file because it is being used by another process
	scons: building terminated because of errors.


	We are running Python 2.6.5 (with pywin32) and SCons 2.3.6. This file is being copied due to a Install() call. Note that, for various historical reasons, we have the following decider for these Installs:


	def _copy_decider(dependency, target, prev_ni):

	    target = str(target.abspath)

	    dependency = str(dependency.abspath)

	    if os.path.isfile(target) and os.path.isfile(dependency):

	        # By default, filecmp.cmp assumes that files with identical os.stat signatures

	        # (which includes the inode) are the same file and, hence, must be the same.

	        # However, on Windows, there is no inode - it appears to be set to zero - so

	        # any two files with the same size and access/creation/modification times

	        # will have the same os.stat signature, leading to a false positive. For this

	        # reason, we must force it to do an actual file comparison by setting shallow

	        # to False

	        return not filecmp.cmp(target, dependency, shallow = False)


	        # Either one of the dependency or target isn't a file or one of the files

	        # (presumably the target) isn't there so do the copy

	        return True


	Note also that our IT department claims that virus checkers are disabled within the directory where the build is being performed (and we certainly have not seen any indication in the virus checker console to suggest that to be incorrect).


	Does anyone have any thoughts as to what the problem might be?


	Thanks in advance,




	Scons-users mailing list
	Scons-users at scons.org



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