Re: [BUG] Unix Builds Requires Pthread Support (was [PATCH v4 00/12] Simple IPC Mechanism)

> On Tue, May 18, 2021 at 07:21:33AM -0400, Jeff Hostetler wrote:
> 
>>> In the simple-ipc API, there's an explicit "async" interface. But it's
>>> not clear to me how rich it expects the communication with the caller to
>>> be (i.e., whether we could get away with the fork() trick here). Or if
>>> it would be OK for the threading to remain an implementation detail,
>>> with one "worker" upon whom we wait for completion.
>>>
>>
>> TBH I forgot that we still support NO_PTHREAD systems.
>> I seem to remember that we got rid of some of the non-pthread
>> stub functions at one point, but I'm fuzzy on the details.
> 
> You're probably thinking of when we got rid of a bunch of #ifdef code
> paths in index-pack, and replaced it with stubs that turn the pthread
> calls into "do nothing" (so all the ugly stuff is in thread-utils.h
> now). But we still very much support systems that don't handle pthreads
> at all.
> 
>> WRT to "simple ipc" (and future "builtin fsmonitor"), it's heavily
>> threaded.  There's no point in trying to fake it with forks.
>>
>> The server side of simple ipc implements a thread pool.  And
>> the builtin fsmonitor will use a thread to monitor FS events
>> and that thread pool to respond to clients.  All driven from a
>> shared queue of events.
>>
>> It would be a major overhaul to do all that without threads
>> -- and even that assumes that nonstop has a sufficient file
>> system notification mechanism.
> 
> OK, that matches my guess from a brief look at the code. Thanks for
> confirming.
> 
>> So, yes, we should ifdef it out as Peff suggests.
> 
> The patch I sent wasn't really tested beyond confirming that "make
> NO_PTHREADS=1" finished compiling (and that test-tool simple-ipc
> barfed appropriately at runtime).
> 
> Do you want to pick it up from there and produce a polished patch? I
> think we should deal with this prior to the v2.32.0 release (and thanks
> Randall for testing and finding it during the -rc0 period).
> 
> -Peff
>