feat: add thread-safe progress meter

[younes-io]

No description provided.

[younes-io]

@timholy could you please take a look at this?
thank you

[MarcMush]

it looks ok but is there a problem you came up across? Does this test something that wasn't tested before?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.77%. Comparing base (807496a) to head (5a73a83).
Report is 22 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #334      +/-   ##
==========================================
+ Coverage   93.48%   96.77%   +3.29%     
==========================================
  Files           1        1              
  Lines         399      559     +160     
==========================================
+ Hits          373      541     +168     
+ Misses         26       18       -8     

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[younes-io]

it looks ok but is there a problem you came up across? Does this test something that wasn't tested before?

I added this to test how threads behave when they're all trying to update the same thing at once, but with different timing patterns. This can catch subtle issues that simpler tests might miss.

[MarcMush]

we've had problems with threading (#232 and linked discussions) and there can be more done to improve multi-threading (#333, #157)

I wrote this to try to catch unsafe threading

ProgressMeter.jl/test/core.jl

Lines 174 to 184 in cd0414f

	function test_thread(N)
	p = Progress(N)
	Threads.@threads for _ in 1:N
	next!(p)
	end
	end
	println("Brute-forcing thread safety... ($(Threads.nthreads()) threads)")
	@time for i in 1:10^5
	test_thread(Threads.nthreads())
	end

I think no sleep is a worst-case, and sleep yields (cpu can do other stuff) which is not a realistic workload either

I would have no problem adding these tests but i don't see what they add. If you have more insight on threaded stuff please say, I'm pretty new to it

[younes-io]

@MarcMush you're right, those tests were just simulating artificial computation.. I wasn't aware of this issue, so I pushed a commit to implement @timholy's recommendation using Threads.@spawn
Obviously, this is just a start.. Please, let me know your thoughts