Hey Brian, Thanks for the input. Yeah making the rx_streamers at the beginning and keeping them around resolves the issue in that test program -- no segfaults after 10000 Rx iterations total from the two threads. Makes sense; if the issue is happening in rx_streamer creation, then we should do that as little as possible. We'd just have to re-create the streamers when we re-tune or some such.
I was perusing the docs and it also seems like there is also a more fundamental misunderstanding on my end. It looks like there can always only be one RX streamer at a time per multi_usrp object as per this little note in the docs: https://files.ettus.com/manual/classuhd_1_1device.html#a0a9e36f353dcce36b4dd8d394c8813e3 unless I misunderstand. Curses! That seems to indicate that I am relying on undefined behavior in either case, even though everything seems to now work as expected. Ideally the UHD would have complained that I was doing that! Ah well. Time to re-architecture some stuff! 🙂 Thank you, Andrew Fountain Black River Systems Co., Inc. 162 Genesee Street Utica, NY 13502 ________________________________ From: Brian Padalino <bpadal...@gmail.com> Sent: Tuesday, August 22, 2023 4:22 PM To: Andrew Fountain <afount...@brsc.com> Cc: usrp-users@lists.ettus.com <usrp-users@lists.ettus.com> Subject: Re: [USRP-users] Re: UHD4 segmentation fault on creating rx_streamer You don't often get email from bpadal...@gmail.com. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> On Tue, Aug 22, 2023 at 4:16 PM Andrew Fountain via USRP-users <usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com>> wrote: Here is the output of that program with a debug build of UHD v4.4.0.0 . It seems to point out this line https://github.com/EttusResearch/uhd/blob/UHD-4.4/host/lib/rfnoc/rfnoc_graph.cpp#L393<https://usg02.safelinks.protection.office365.us/?url=https%3A%2F%2Fgithub.com%2FEttusResearch%2Fuhd%2Fblob%2FUHD-4.4%2Fhost%2Flib%2Frfnoc%2Frfnoc_graph.cpp%23L393&data=05%7C01%7Cafountain%40brsc.com%7C080e13d2bdc743f6fddd08dba34d96b2%7C5ed13283606a46b1bd4f758a462df882%7C1%7C0%7C638283325860702606%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=DgXydmUT8Sx3Ut50BrPNkaBRYTbXTYO2O80zpAu%2F%2Fy4%3D&reserved=0> It doesn't seem to be some weird threading issue related to getting multiple rx_streamers at the same time; adding a lock around that access to that get_rx_stream function still yields segmentation faults at the same point in get_rx_stream. Are you sure? Can you move the streamer creation to be outside of the for loop and just iterate on the stream args, issue command, and recv()? Brian
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