Bug 1787914
| Summary: | stream does not work in non-block mode with event loop implementation on Fibers | ||||||||
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| Product: | [Community] Virtualization Tools | Reporter: | Denis <senid231> | ||||||
| Component: | ruby-libvirt | Assignee: | Libvirt Maintainers <libvirt-maint> | ||||||
| Status: | NEW --- | QA Contact: | |||||||
| Severity: | high | Docs Contact: | |||||||
| Priority: | unspecified | ||||||||
| Version: | unspecified | CC: | clalancette, senid231 | ||||||
| Target Milestone: | --- | Keywords: | Reopened | ||||||
| Target Release: | --- | ||||||||
| Hardware: | x86_64 | ||||||||
| OS: | Linux | ||||||||
| Whiteboard: | |||||||||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |||||||
| Doc Text: | Story Points: | --- | |||||||
| Clone Of: | Environment: | ||||||||
| Last Closed: | 2025-10-17 00:11:00 UTC | Type: | Bug | ||||||
| Regression: | --- | Mount Type: | --- | ||||||
| Documentation: | --- | CRM: | |||||||
| Verified Versions: | Category: | --- | |||||||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||||
| Embargoed: | |||||||||
| Attachments: |
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Sorry for bad English. if you call the script with GC_DISABLE=1 env screenshot will be saved correctly. It means that GC removes last reference for passthrough while it's still in use. I have another hotfix for that. I've just return passthrough from stream_event_add_callback function and store it in instance variable of singleton until streaming is finished/failed/cancelled. Adding Chris, who has the most knowledge in these bindings. same bug at ext/libvirt/connect.c:812 libvirt_connect_domain_event_register_any passthrough is created as ruby object and later will be destroyed by GC by temporary solution similar with previous problem - I just return passthrough to ruby code and store it until event is deregistered But it looks very ugly from my side. I think proper way to handle such case would be to say GC to ignore this object and clean it manually (maybe bind it to C object and free on destruction). Created attachment 1652211 [details]
patch that fixes issue
I've found better way to handle this. I store *passthrough* in as instance variable until it no longer needed.
Take a look at the patch in attachments
Update Looks like ruby-libvirt is not maintained anymore. I found another bug with GC (looks like GC frees stream which still has references) and memory leak (each time screenshot is taken it leaks 1-3mb). I've decided to rewrite ruby implementation using FFI. I've implemented main functions from host, domain and screenshot parts. And currently, there are no memory leaks or GC issues found. If someone encounters similar problems you can try my implementation on GitHub (senid231/libvirt_ffi). https://github.com/senid231/libvirt_ffi PS Also, I've found another bug related to libvirtd restarting. When the server restarts client application hangs because the libvirt C code tries to acquire the same lock twice in the same thread. Currently, this issue reproduced in my implementation too. I'm planning to fix it soon. This product has been discontinued or is no longer tracked in Red Hat Bugzilla. Reopening because Virtualization Tools has not been discontinued. |
Created attachment 1649958 [details] script that reproduces an error Description of problem: libvirt_stream_event_add_callback creates passthrough variable using rb_ary_new2 and pass it to virStreamEventAddCallback at ext/libvirt/stream.c:272. After that ruby garbage collector removes this variable (I think because there is no references for passthrough in ruby code). Version-Release number of selected component (if applicable): ruby-libvirt-0.7.1 How reproducible: can be reproduced using libvirt fibers. script provided in attachments. Steps to Reproduce: 1. use ruby >= 2.4.4 2. gem install ruby-libvirt -v 0.7.1 3. gem install libvirt_async -v 0.2.1 4. ruby test_ruby_libvirt_stream.rb HV_URI DOMAIN_UUID replace HV_URI with your hypervisor URI replace DOMAIN_UUID with your domain UUID Actual results: TypeError: wrong domain event lifecycle callback argument type (expected Array) script does not exit because it wait callback to be called Expected results: screenshot saved /current/path/screenshot.pnm exit 0 Additional info: if you call script disable GC during script like this GC_DISABLE=1 ruby test_ruby_libvirt_stream.rb HV_URI DOMAIN_UUID it will work correctly