https://github.com/scarfacedeb/dump_server
An experiment to create a dump server to get ObjectSpace information from the running rails app
https://github.com/scarfacedeb/dump_server
Last synced: 2 months ago
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An experiment to create a dump server to get ObjectSpace information from the running rails app
- Host: GitHub
- URL: https://github.com/scarfacedeb/dump_server
- Owner: scarfacedeb
- Created: 2014-10-03T11:57:36.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2014-10-03T12:47:58.000Z (over 10 years ago)
- Last Synced: 2025-03-14T05:02:12.381Z (3 months ago)
- Language: Ruby
- Size: 156 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
dump_server
===========
An experiment to create a dump server to get GC information from the running rails app.
Goals:
-----
- Get ObjectSpace and Garbage Collector information about running apps.
- Minimize or eliminate probe effect.
- Make it work over unix socket.
Approaches:
-----
- Use a method inside the app (e.g. an action in controller).
**Result:** it's the easiest approach, but probably it's the most useless, because making a request creates a lot of overhead when fetching the data. (i.e. probe effect is huge)
- Create a dump server that will run in a separate thread and would talk over unix socket.
**Result:** the probe effect is minimal, it's the most stable and less invasive approach. (the best results so far)
- Use raw gdb to attach to the ruby process, eval ruby code, detach.
**Result:** process hangs after detach
- Use [hijack](https://github.com/ileitch/hijack) to simplify attachment with gdb.
**Result:** Compared to the dump server approach, it's not as stable, but the probe effect is almost the same.
Dump server
------
[Dump server](lib/dump_server.rb) implemented to talk over `/tmp/dump_server.sock` unix socket.
It's running inside a separate thread to prevent blocking of the main thread.
It uses forking technique, based on the [Faster Rails test runs...with Unix!](http://www.jstorimer.com/blogs/workingwithcode/8136295-screencast-faster-rails-test-runs-with-unix) screencast by Jesse Storimer. That technique is used to minimize the probe effects. (*Is it really needed in this case?*)
The dump server is required inside an initializer that also disables the GC. (*for testing purposes*)
You can use [demo socket client](lib/dump_client.rb) to get the `ObjectSpace.count_objects` from the running rails app.
Experiments
----------
Fetch the `ObjectSpace.count_objects` information twice to measure the **difference** between the results.
It would allow to crudely estimate the probe effect of the given approaches.
> Garbage collector is disabled
**App request:**
```ruby
{:TOTAL=>14675, :FREE=>74, :T_OBJECT=>337, :T_CLASS=>0, :T_MODULE=>0, :T_FLOAT=>0, :T_STRING=>7834, :T_REGEXP=>26, :T_ARRAY=>3133, :T_HASH=>295, :T_STRUCT=>54, :T_BIGNUM=>0, :T_FILE=>5, :T_DATA=>636, :T_MATCH=>427, :T_COMPLEX=>0, :T_RATIONAL=>0, :T_NODE=>1854, :T_ICLASS=>0}
```
**Dump server:**
```ruby
{:TOTAL=>0, :FREE=>-96, :T_OBJECT=>1, :T_CLASS=>0, :T_MODULE=>0, :T_FLOAT=>0, :T_STRING=>0, :T_REGEXP=>0, :T_ARRAY=>47, :T_HASH=>0, :T_STRUCT=>0, :T_BIGNUM=>0, :T_FILE=>1, :T_DATA=>47, :T_MATCH=>0, :T_COMPLEX=>0, :T_RATIONAL=>0, :T_NODE=>0, :T_ICLASS=>0}
```
**Hijack:**
```ruby
{:TOTAL=>0, :FREE=>-84, :T_OBJECT=>1, :T_CLASS=>0, :T_MODULE=>0, :T_FLOAT=>0, :T_STRING=>38, :T_REGEXP=>0, :T_ARRAY=>25, :T_HASH=>1, :T_STRUCT=>0, :T_BIGNUM=>0, :T_FILE=>0, :T_DATA=>15, :T_MATCH=>0, :T_COMPLEX=>0, :T_RATIONAL=>0, :T_NODE=>4, :T_ICLASS=>0}
```