I just stumbled upon something odd in package.bbclass. In commit
ede381d5 from January 2011 (the code hasn't changed since), the
use of the ${PACKAGELOCK} lock file was changed to shared to
improve parallelism. However, when looking at the actual change
it becomes confusing. I have included it below for reference.
> commit ede381d56b180b384fdad98d445e5430819cfade
> Author: Richard Purdie <richard.pur...@linuxfoundation.org>
> Date: Wed Jan 19 11:04:15 2011 +0000
>
> package.bbclass: Take a shared lock when reading to improve do_package
> parallelism
>
> Signed-off-by: Richard Purdie <richard.pur...@linuxfoundation.org>
>
> diff --git a/meta/classes/package.bbclass b/meta/classes/package.bbclass
> index d39c694de5..8e7fa26f72 100644
> --- a/meta/classes/package.bbclass
> +++ b/meta/classes/package.bbclass
> @@ -497,7 +497,8 @@ python emit_pkgdata() {
> pkgdest = bb.data.getVar('PKGDEST', d, 1)
> pkgdatadir = bb.data.getVar('PKGDESTWORK', d, True)
>
> - lf = bb.utils.lockfile(bb.data.expand("${PACKAGELOCK}", d))
> + # Take shared lock since we're only reading, not writing
> + lf = bb.utils.lockfile(bb.data.expand("${PACKAGELOCK}", d), True)
Here the lock is changed to shared as per the commit message.
>
> data_file = pkgdatadir + bb.data.expand("/${PN}" , d)
> f = open(data_file, 'w')
> @@ -649,6 +650,7 @@ python package_do_shlibs() {
> shlibs_dir = bb.data.getVar('SHLIBSDIR', d, True)
> shlibswork_dir = bb.data.getVar('SHLIBSWORKDIR', d, True)
>
> + # Take shared lock since we're only reading, not writing
> lf = bb.utils.lockfile(bb.data.expand("${PACKAGELOCK}", d))
Here, however, it is not changed, even though a comment is added to
say that it is. Was this intentional, or just an oversight?
>
> def linux_so(root, path, file):
> @@ -878,6 +880,7 @@ python package_do_pkgconfig () {
> if hdr == 'Requires':
>
> pkgconfig_needed[pkg] += exp.replace(',', ' ').split()
>
> + # Take shared lock since we're only reading, not writing
> lf = bb.utils.lockfile(bb.data.expand("${PACKAGELOCK}", d))
Here again a comment is added, but the code is not changed to match.
>
> for pkg in packages.split():
Also, what is the ${PACKAGELOCK} lock file actually protecting? With
the exception of the two questionable cases above, I cannot see that
the lock is taken privately anywhere else. And since it looks as the
code in package_do_shlibs() and package_do_pkgconfig() is not what
needs protection (based on the added comments above), what is?
//Peter
--
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