feat: Merge threads in live view

[mgmacias95]

Issue number of the reported bug or feature request: #587

Describe your changes
This PR adds a new option in the live view called "merge threads" that summarizes all allocations in a single view. It also hides the buttons ">" and "<" because you can't move between threads in that moment.

In addition, I added some missing docs to the readme.

Testing performed
Manual testing + unit tests included in this PR

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 98.83721% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 92.93%. Comparing base (41248ed) to head (807f71b).
Report is 47 commits behind head on main.

Files	Patch %	Lines
src/memray/reporters/_textual_hacks.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #589      +/-   ##
==========================================
+ Coverage   92.55%   92.93%   +0.38%     
==========================================
  Files          91       92       +1     
  Lines       11304    11307       +3     
  Branches     1581     2076     +495     
==========================================
+ Hits        10462    10508      +46     
+ Misses        837      799      -38     
+ Partials        5        0       -5     

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cpp	92.93% <98.83%> (+6.99%)	⬆️
python_and_cython	92.93% <98.83%> (-2.79%)	⬇️

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[godlygeek]

This seems like a great start, but I'm spotting lots of little issues as I try to use it.

For one, if the process is still running and output isn't paused, then threads seem to become un-merged again as soon as the next update happens.

For another, this disables the < and > keys, but not the left and right arrow keys, which do the same thing (as long as the grid isn't wide enough to scroll - if it is, they scroll the grid instead).

Also, if after the tracked process dies you use the > key to select a specific thread and then enable thread merging, the table doesn't get redrawn to include allocations from all threads, even though the header gets redrawn to say that allocations from all threads are being shown together.

Can you spend some time tracking down and fixing these issues?

[mgmacias95]

Hello @godlygeek,

I plan working on this by the end of the week. Thank you for your review! :)

[mgmacias95]

Hey @godlygeek,

So when I said I would work on this by the end of the week, I meant by the end of the day 😅 😂

I fixed the issues you pointed out. Can you please review it again?

Thanks!

[godlygeek]

It looks like, while it's in "merge threads" mode, the header winds up incorrectly showing a thread count again the first time a new thread is created after entering "merge threads" mode. See this screenshot, for instance:

You'll see that it shows "Thread 1 of 23" at the top, but "M Unmerge threads" at the bottom, so it's still in merge threads mode, but incorrectly showing a thread index and thread count.

Try using this test program:

import mmap
import threading
import time


def allocate():
    with mmap.mmap(-1, 1024 * 1024):
        time.sleep(1)


threads = [threading.Thread(target=allocate) for _ in range(3)]
for thread in threads:
    time.sleep(3)
    thread.start()

and pressing "m" to merge threads as soon as the TUI shows up. You'll see that the heading switches to saying "Displaying all threads." but as soon as a new thread shows up, it switches back to displaying a thread count.

[mgmacias95]

Hello @godlygeek,

Thank you for your review again, I just pushed a commit fixing that problem. Can you take another look? Thanks!

Cheers!

[mgmacias95]

Hello @godlygeek,

I have fixed some conflicts that appeared in 2f50fa7. Can you take a look again please? 🥺

Thanks!