How to diagnose hashcat progress stalling?

[serious-business]

First, I would NOT attempt to use the CPU device at the same time as the GPU device. This will only lead to worse overall performance in the majority of cases, especially on an already weak system.

I accidentally did leave 1 on the -D flag (thought it meant order of preference of device type), but I only ended up using the discrete and integrated GPUs with -d 1,2, which are  

Code:

Metal Info:
===========

Metal.Version.: 343.21

Backend Device ID #01 (Alias: #05)
  Type...........: GPU
  Vendor.ID......: 2
  Vendor.........: Apple
  Name...........: AMD Radeon Pro Vega 20
...

Backend Device ID #02 (Alias: #04)
  Type...........: GPU
  Vendor.ID......: 2
  Vendor.........: Apple
  Name...........: Intel(R) UHD Graphics 630
...

I actually did try to use my CPU device (#3) with the GPUs, but -d 1,2,3 would result in hashcat skipping the GPUs and only using the CPU.

Second, how big is your dictionary? What is the mask you are trying to run? Perhaps this is a workload issue leading to a low power or idle state, but it's impossible to tell without some more information. I suspect it's not, but worth investigating that avenue first as it's an easy fix.

Keyspace was 501972000, with both GPUs getting 62357 H/s and an estimated time to completion of just 2 hours, 12 mins.  Doing a quick test now, that estimate seems about right, because it did 4.45% progress in ~5 minutes.  

And that type of performance is fine by me, except that 2 hours extends to 2 days, because I start hc, monitor it for a bit, think, "wow, it sure is working fast", then leave and come back to find progress has stalled.  Then I have to hit 'q' to exit, and restart the session, hoping hc had reached the next restore point.  

The issue shouldn't be low power.  I know this particular MacBook is brilliantly designed, so that even if it's plugged in to a high-wattage power adapter, using the dGPU causes the battery level to drop, and I think at 20% the dGPU gets shut off.  In running hc, I never saw the battery get that low (hc is always idling by then), and anyway, wouldn't the iGPU keep working without the dGPU?

I dealt with idle sleeping by using the macOS caffeinate command, which "creates assertions to alter system sleep behavior."  I even tried preventing the display from sleeping, and that didn't stop hc from stalling.

For this reply, I started an hc session, and it ran 47 mintues before I caught it not working.  At 32.14% progress, it was alive, and at 32.18% progress it was dead.  Battery was 52% (but maybe it had gone down to 50%?), and I was at the laptop the whole time with the display on.

Thank you, I hope I answered all your questions.  I suppose my next step is to check if 50% battery is the killer threshold.