Add option to jl_print_task_backtraces(bool) to control whether or not to print DONE tasks

[NHDaly]

This lets you print all live tasks, with less noise in the logs, in case it's been a while since the last GC.

In some cases, we are seeing many thousands of DONE Tasks, which greatly increase the noise in the logs, and can overwhelm the DataDog logging.

This addresses part of the logging issues identified in #47932.

@vilterp and @msagarpatel for review.

[vilterp]

I kind of just want to change jl_print_backtraces to be this — i.e. to always skip tasks that are done. I can't think of a case where I'd want to see them 🤔

[kpamnany]

I kind of just want to change jl_print_backtraces to be this — i.e. to always skip tasks that are done. I can't think of a case where I'd want to see them 🤔

Right now it's not very useful but I haven't given up on a task naming scheme; with that it would be possible to tell which task was completed and that could be useful information. For now though, you're right that having done tasks in this list don't really add value.

[NHDaly]

I just came back here to say the same thing as Pete. I was thinking about this when brushing my teeth just now, and indeed it seems like it'd be better to just always turn this off, without a parameter. And if we ever find some situation in the future, like named tasks, where we want it again, we could turn it back on or add a param?

But I'm open to keeping the param now if you do feel that there's value! But yeah, my gut leans the same as Pete's.

@kpamnany: what do you think for a final call?

[kpamnany]

Yeah, I think an int parameter makes the interface a bit more future-proof.

[NHDaly]

Hokay, per popular consensus, i have switched to a boolean parameter. 0 means don't show the completed tasks. 1 means do show completed tasks. I think that in most cases, most users will want 0, but sometimes they may want 1 (such as to check for the pointer to a task that they expect to be there).

[NHDaly]

Please take a final look. This should be backported to 1.9, since it is modifying a not-yet-released feature.

[NHDaly]

thanks, merged.