On start up two Mu instances race each other and crash

[carlosperate]

All the log entries for the crashed session are duplicated, and then Mu crashes at points where it check if a directory exists (it doesn't at the time), and then fails to create it because the other instance won the race.

For example:

mu/mu/logic.py

Lines 796 to 798 in 9179f64

	if not os.path.exists(wd):
	logger.debug("Creating directory: {}".format(wd))
	os.makedirs(wd)

I'm pretty sure I've seen this myself once on Windows, although I couldn't replicate after. I didn't do it intentionally, so I don't if I accidentally double clicked more than once, or something similar, my assumption is that this was an "user mistake", but I am not sure.

We might want to reconsider or revisit this:

• Single instance application #276.

Crash reports affected (won't be merged here yet to try to ask the individual users to check if this is indeed the problem):

• Crash report - FileExistsError with mu_code\templates #1506
• Crash Report #1702
• Crash Report #1712
• Crash Report #1725
• Crash Report #1879
• Crash Report #1964
• Crash Report #1987
• Crash Report crash-reports#81
• Crash Report crash-reports#209
• Crash Report crash-reports#242
• Crash Report crash-reports#249
• Crash Report crash-reports#250
• Crash Report crash-reports#465
• Crash Report crash-reports#487
• Crash Report crash-reports#507
• Crash Report crash-reports#596
• Crash Report crash-reports#612
• Crash Report crash-reports#614
• Crash Report crash-reports#622

And these are possible candidates, but we won't know until the logs are shared:

• Crash Report - Error creating mu_code directory #1535
• Install issue #1566
• Crash Report #1681
• Crash Report #1706
• Crash Report #1739
• Crash Report #1742
• Crash Report #1786
• Crash Report #1855
• Crash Report #1881
• C:\Users\markf\AppData\Local\python\mu\Logs\mu.log #1890
• Crash Report #1892
• Crash Report #1896
• Crash Report #1903
• This Popped up on First Start - But then it worked --- Crash Report #1948
• Crash Report #2100
• Crash Report #2123
• Crash Report crash-reports#82
• Crash Report crash-reports#86
• Crash Report crash-reports#88
• Crash Report crash-reports#87
• Crash Report crash-reports#89
• Crash Report crash-reports#90
• Crash Report crash-reports#91
• Crash Report crash-reports#92
• Crash Report crash-reports#93
• Crash Report crash-reports#94
• Crash Report crash-reports#99
• Crash Report crash-reports#270
• Crash Report crash-reports#279
• Crash Report crash-reports#344
• Crash Report crash-reports#355
• Crash Report crash-reports#392
• Crash Report crash-reports#397
• Crash Report crash-reports#401
• Crash ReportC:\Users\gonda\AppData\Local\python\mu\Logs\mu.log crash-reports#412
• Crash Report crash-reports#430
• Crash Report - first time run crash-reports#436
• Crash Report crash-reports#476
• Crash Report crash-reports#483
• Crash Report crash-reports#494
• Crash Report crash-reports#504
• Crash Report crash-reports#513
• Crash Report crash-reports#517
• Crash Report - Mu crash-reports#520
• Crash Report crash-reports#537
• Crash Report crash-reports#547
• Crash Report crash-reports#550
• Crash Report crash-reports#602
• Crash Report crash-reports#627

[carlosperate]

As noted in #1762, since the Mu startup takes a long time, users are more likely going to try to relaunch the application, making this issue more common.

I've also noticed that in my Windows environment it takes a few seconds for the splash screen to appear after I click on the Mu shortcut, so even I was very tempted to reopen it at that point, thinking that maybe I didn't click it correctly.