avoid self.targets is nil.

[juzipeek]

when two worker create checker, worker-0 first created and add target success, then worker-1 creating, when worker-1 call worker_events:poll() in line 1408, raise crash.
self.targets init with empty table avoid this.

[Tieske]

@juzipeek I'm not sure this fix is correct.

That table (which you are initializing) is already initialized here:

lua-resty-healthcheck/lib/resty/healthcheck.lua

Line 1410 in aab3701

self.targets = target_list

If it is not initialized, then it failed to acquire the lock, with should result in this code:

lua-resty-healthcheck/lib/resty/healthcheck.lua

Lines 1427 to 1431 in aab3701

	if not ok then
	-- locking failed, we don't protect `targets` of being nil in other places
	-- so consider this as not recoverable
	return nil, "Error loading initial target list: " .. err
	end

exiting early and returning the error.

So effectively the call to poll should never execute (

lua-resty-healthcheck/lib/resty/healthcheck.lua

Line 1440 in aab3701

worker_events.poll()

)

So what was the initial error you got? Or can you provide a testcase demonstrating the issue?

[Tieske]

looks same as #42

[Tieske]

reconsidering this, since it is async, it might not be initialized, so this is a proper fix