Fix segmentation fault when using jq in threads

[thalman]

In previous code nomem_handler in jv_alloc.c is called only once and therefore the structure is not initialized for second and following threads.

This leads to segmentation fault in multi-threading environment.

This patch moves initialization of nomem_handler out of the pthread_once call.

This patch fixes the issue #2545

[edwardb96]

I think this is related to #2483 and #2484 - but given it's been 6 months I'm not sure I'd hold out much hope.

[thalman]

@edwardb96 I see, you are right. This is the same issue. I do not mind if my patch is not selected, but what prevents merging one of those?

I'm about to include one of them to Fedora and RHEL anyway.

Tom

[wader]

Hi, thanks both for the PRs, see #2305 for current state of the project

[nicowilliams]

Let's make sure we review this and related issues/PRs before we release, no? I'll see if I can find time this week.

[wader]

Maybe this one should be added to https://github.com/jqlang/jq/milestones/1.7%20release? it's the list i've picked things from.

@itchyny wrote about a release plan here #2623 (comment)

[itchyny]

@nicowilliams Thank you. Very appreciated, and I added this to the milestone.

[thalman]

Thank you, guys for taking care of this issue. Let me know if you need anything from my side.

[wader]

@thalman Hi, can you rebase on master? the CI should work better now

[thalman]

@thalman Hi, can you rebase on master? the CI should work better now

@wader, rebased. Thanks for the CI work!

[wader]

Do you know if this is a regression? i haven't linked with libjq myself but looking at the jq code it seems to have quite a lot of code to be thread safe, but was is never really tested or it broke at some point?

Thanks for adding a test btw!

[thalman]

The bug is not present in 1.5. It was introduced later on in commit 3f86e97

I would not call that regression. It brings a new functionality that allows different no_mem_handler for different threads, it just did not work properly and it was not tested in more threads.

[nicowilliams]

Thanks!!