Add a lock to protect pushes to results

[giordano]

Taken out of #119, ref: #119 (comment).

[maleadt]

We also need this on the read operations, no? At least when multithreading; I assume with regular concurrent @async this would work fine without (or at least I assumed so when writing this code).

[giordano]

We also need this on the read operations, no?

There weren't other uses of results in the worker tasks @async block

ParallelTestRunner.jl/src/ParallelTestRunner.jl

Lines 1024 to 1108 in 557d7fd

	push!(worker_tasks, @async begin
	while !done
	# get a test to run
	test, test_t0 = Base.@lock test_lock begin
	isempty(tests) && break
	test = popfirst!(tests)
	test_t0 = time()
	running_tests[test] = test_t0
	test, test_t0
	end
	# pass in init_worker_code to custom worker function if defined
	wrkr = if init_worker_code == :()
	test_worker(test)
	else
	test_worker(test, init_worker_code)
	end
	if wrkr === nothing
	wrkr = p
	end
	# if a worker failed, spawn a new one
	if wrkr === nothing || !Malt.isrunning(wrkr)
	wrkr = p = addworker(; init_worker_code, io_ctx.color)
	end
	# run the test
	put!(printer_channel, (:started, test, worker_id(wrkr)))
	result = try
	Malt.remote_eval_wait(Main, wrkr.w, :(import ParallelTestRunner))
	Malt.remote_call_fetch(invokelatest, wrkr.w, runtest,
	testsuite[test], test, init_code, test_t0)
	catch ex
	if isa(ex, InterruptException)
	# the worker got interrupted, signal other tasks to stop
	stop_work()
	break
	end
	ex
	end
	test_t1 = time()
	output = Base.@lock wrkr.io_lock String(take!(wrkr.io))
	Base.@lock results_lock push!(results, (test, result, output, test_t0, test_t1))
	# act on the results
	if result isa AbstractTestRecord
	put!(printer_channel, (:finished, test, worker_id(wrkr), result))
	if anynonpass(result[]) && args.quickfail !== nothing
	stop_work()
	break
	end
	if memory_usage(result) > max_worker_rss
	# the worker has reached the max-rss limit, recycle it
	# so future tests start with a smaller working set
	Malt.stop(wrkr)
	end
	else
	# One of Malt.TerminatedWorkerException, Malt.RemoteException, or ErrorException
	@assert result isa Exception
	put!(printer_channel, (:crashed, test, worker_id(wrkr)))
	if args.quickfail !== nothing
	stop_work()
	break
	end
	# the worker encountered some serious failure, recycle it
	Malt.stop(wrkr)
	end
	# get rid of the custom worker
	if wrkr != p
	Malt.stop(wrkr)
	end
	Base.@lock test_lock begin
	delete!(running_tests, test)
	end
	end
	if p !== nothing
	Malt.stop(p)
	end
	end)

but there were a couple of reads of results inside update_status(), which I just locked. Other uses I can see are all after the tasks are done. Am I missing something else?