On Friday, 20 April 2018 at 18:30:30 UTC, Matthias Klumpp wrote:
On Friday, 20 April 2018 at 05:32:32 UTC, Dmitry Olshansky
wrote:
On Friday, 20 April 2018 at 00:11:25 UTC, Matthias Klumpp
wrote:
On Thursday, 19 April 2018 at 18:45:41 UTC, kinke wrote:
[...]
[...]
I think the order of operations is wrong, here is an example
from containers:
allocator.dispose(buckets);
static if (useGC)
GC.removeRange(buckets.ptr);
If GC triggers between dispose and removeRange, it will likely
segfault.
Indeed! It's also the only place where this is shuffled around,
all other parts of the containers library do this properly.
The thing I wonder about is though, that the crash usually
appeared in an explicit GC.collect() call when the application
was not running multiple threads. At that point, the GC - as
far as I know - couldn't have triggered after the buckets were
disposed of and the ranges were removed. But maybe I am wrong
with that assumption.
This crash would be explained perfectly by that bug.
Turns out that was indeed the case! I created a small testcase
which managed to very reliably reproduce the issue on all
machines that I tested it on. After reordering the
dispose/removeRange, the crashes went away completely.
I submitted a pull request to the containers library to fix this
issue: https://github.com/dlang-community/containers/pull/107
I will also try to get the patch into the components in Debian
and Ubuntu, so we can maybe have a chance of updating the
software center metadata for Ubuntu before 18.04 LTS releases
next week.
Since asgen uses HashMaps for pretty much everything, an most of
the time with GC-managed elements, this should improve the
stability of the application greatly.
Thanks a lot for the help in debugging this, I learned a lot
about DRuntime internals in the process. Also, it is no
exaggeration to say that the appstream-generator project would
not be written in D (there was a Rust prototype once...) and I
would probably not be using D as much (or at all) without the
helpful community around it.
Thank you :-)
