multiple processes intermittently stall at same point in strace
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Expired
|
Undecided
|
Unassigned |
Bug Description
If this isn't a kernel bug, my apologies. I didn't know where else to put it. It affects seemingly unrelated processes, so there wasn't an obvious 'package'. Possibly nscd, which is in glibc, which is close to the kernel...
I noticed frequent, but intermittent hangs/stalls in multiple processes. The processes usually go on to completion after a few seconds or so. Occasionally, I get timeouts that I think might be this same symptom but aren't always strace-able.
At first, I thought it was an authentication issue because I got hangs with "sudo -i" as well as intermittently very slow logins via ssh with ldap. But, then it happened with "vim dum", which could still be authentication somehow, but I don't know enough to determine that. Htop will also hang intermittently, but I don't have a trace of it.
I started running strace on the processes that are hanging. The hang happened after the same few lines each time that I was able to strace at the same time of a hang (it is intermittent).
Here is an example of the last lines before hang where a normal user issues "strace id username":
socket(AF_UNIX, SOCK_STREAM|
connect(3, {sa_family=AF_UNIX, sun_path=
sendto(3, "\2\0\0\
poll([{fd=3, events=
<detached ...>
I hit ctrl-C to stop execution so I could easily copy that info, hence detached.
Here is an example from root using "strace vim dum":
poll([{fd=3, events=
...that took practice to capture.
I suspect that LDAP is involved somehow, but it might be victim rather than culprit. Obviously, nscd has some involvement per the lines above. Or possibly, these lines are about strace itself?
I can capture full straces with timings, etc. Just say what you need. Or direct me to the proper venue for this report.
I looked in kern.log for evidence of a hardware issue, but didn't see anything that looked significantly unusual. If it seems like hardware, I will appreciate hints as to the component.
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-image-
ProcVersionSign
Uname: Linux 5.4.0-40-generic x86_64
NonfreeKernelMo
ApportVersion: 2.20.11-0ubuntu27.3
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/
CasperMD5CheckR
CurrentDesktop: LXDE
Date: Thu Jul 2 04:36:12 2020
InstallationDate: Installed on 2020-06-25 (7 days ago)
InstallationMedia: Ubuntu-MATE 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
MachineType: HP ProLiant DL380 G7
ProcFB: 0 VESA VGA
ProcKernelCmdLine: BOOT_IMAGE=
RelatedPackageV
linux-
linux-
linux-firmware 1.187.1
RfKill:
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/05/2011
dmi.bios.vendor: HP
dmi.bios.version: P67
dmi.chassis.type: 23
dmi.chassis.vendor: HP
dmi.modalias: dmi:bvnHP:
dmi.product.family: ProLiant
dmi.product.name: ProLiant DL380 G7
dmi.product.sku: 583917-B21
dmi.sys.vendor: HP
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