Add Clean Up Memory-Hungry Rails Console Processes as a Rails TIL

README.md

@@ -10,7 +10,7 @@ working across different projects via [VisualMode](https://www.visualmode.dev/).
 
 For a steady stream of TILs, [sign up for my newsletter](https://visualmode.kit.com/newsletter).
 
-_1729 TILs and counting..._
+_1730 TILs and counting..._
 
 See some of the other learning resources I work on:
 
@@ -1073,6 +1073,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Check If ActiveRecord Update Fails](rails/check-if-activerecord-update-fails.md)
 - [Check If Any Records Have A Null Value](rails/check-if-any-records-have-a-null-value.md)
 - [Check Specific Attributes On ActiveRecord Array](rails/check-specific-attributes-on-activerecord-array.md)
+- [Clean Up Memory Hungry Rails Console Processes](rails/clean-up-memory-hungry-rails-console-processes.md)
 - [Code Statistics For An Application](rails/code-statistics-for-an-application.md)
 - [Columns With Default Values Are Nil On Create](rails/columns-with-default-values-are-nil-on-create.md)
 - [Comparing DateTimes Down To Second Precision](rails/comparing-datetimes-down-to-second-precision.md)

rails/clean-up-memory-hungry-rails-console-processes.md

@@ -0,0 +1,43 @@
+# Clean Up Memory Hungry Rails Console Processes
+
+I noticed (using `htop`) that a remote server hosting a Rails app had most of
+its RAM being actively consumed. This was hindering my ability to run a fresh
+deploy because the deploy processes had to do a ton of memory swapping which
+drastically slowed the whole thing down.
+
+With some investigation, I discovered that most of the memory was being consumed
+by a handful of `rails console` processes. I didn't have any known active `rails console` processes that I was using. That combined with the dates of these
+processes starting way in the past suggested to me that these were abandoned
+processes that hadn't been properly cleaned up.
+
+```bash
+server:~# ps aux | grep rails
+32767     878915  0.0  0.0 1227160  936 pts/0    Ssl+  2025   0:03 /exec rails console
+32767     878942  0.9  6.5 830996 261748 pts/0   Rl+   2025 249:51 ruby /app/bin/rails console
+32767    3004097  0.0  0.0 1227160  692 pts/0    Ssl+  2025   0:04 /exec rails console
+32767    3004129  0.9  6.4 834672 257228 pts/0   Dl+   2025 406:31 ruby /app/bin/rails console
+32767    3048582  0.0  0.0 1227160  940 pts/0    Ssl+ Jan09   0:00 /exec rails console
+32767    3048611  1.1  6.3 829936 253484 pts/0   Dl+  Jan09  60:50 ruby /app/bin/rails console
+32767    3060033  0.0  0.0 1227160  944 pts/0    Ssl+  2025   0:04 /exec rails console
+32767    3060063  0.9  6.5 838084 260812 pts/0   Rl+   2025 405:37 ruby /app/bin/rails console
+root     3699372  0.0  0.0   7008  1300 pts/0    S+   15:51   0:00 grep --color=auto rails
+server:~# ps aux | grep 'rails console' | awk '{sum+=$6} END {print sum/1024 " MB"}'
+1014.64 MB
+```
+
+As we can see by tacking on this `awk` command, these processes are consuming
+1GB of memory.
+
+Each of these is a pair of processes. A parent process (`/exec rails console`)
+that kicks off and supervises the memory-hungry child process (`ruby /app/bin/rails console`).
+
+To free up this memory, I targeted each of the parent processes with a `kill`
+command one by one. For example:
+
+```bash
+server:~# kill 878915
+```
+
+I suspect that I may have left the occasional terminal tab open with one of
+these `rails console` processes running and the SSH connection was getting
+killed without the `rails console` getting killed with it.