[feature wanted] thread safe method to flush counters in dataplane

[w1nda]

We need a thread safe method to flush counters in dataplane, as there may many thread sharing the same dataplane instance:(

ptf/src/ptf/__init__.py

Line 20 in c554f83

dataplane_instance = None

Counters:

ptf/src/ptf/dataplane.py

Lines 571 to 575 in c554f83

	# counters of received packets (may include packets which were dropped due to queue overflow)
	self.rx_counters = defaultdict(int)
	# counters of transmited packets
	self.tx_counters = defaultdict(int)

[jafingerhut]

Would something as straightforward as acquiring a lock around all accesses to rx_counters / tx_counters do what you are asking for? If so, are you interested in submitting a PR for review that does this?