The multiple drivers need to sync up on before starting benchmark

[rdiyewar]

I am using 4 drivers (client instances) in a benchmark, however they are not in sync, resulting into incorrect benchmark results. They starts ony afer other but do not sync up, thus first driver who comes up starts benchamrk operations firsts and so finishes first.

See the time difference between starting of each driver.

$ grep "Starting main test (warmup finished)" logs_drivers/*
logs_drivers/131936_0_pnq-gst-dev06.log:<13:20:34><yardstick> Starting main test (warmup finished).
logs_drivers/131949_1_pnq-gst-dev06.log:<13:20:45><yardstick> Starting main test (warmup finished).
logs_drivers/132002_2_pnq-gst-dev06.log:<13:20:58><yardstick> Starting main test (warmup finished).
logs_drivers/132015_3_pnq-gst-dev06.log:<13:21:12><yardstick> Starting main test (warmup finished).

Same with test finish:

$ grep "Finishing main test" logs_drivers/*
logs_drivers/131936_0_pnq-gst-dev06.log:Finishing main test [ts=1436255734062, date=Tue Jul 07 13:25:34 IST 2015]
logs_drivers/131949_1_pnq-gst-dev06.log:Finishing main test [ts=1436255745000, date=Tue Jul 07 13:25:45 IST 2015]
logs_drivers/132002_2_pnq-gst-dev06.log:Finishing main test [ts=1436255758933, date=Tue Jul 07 13:25:58 IST 2015]
logs_drivers/132015_3_pnq-gst-dev06.log:Finishing main test [ts=1436255772103, date=Tue Jul 07 13:26:12 IST 2015]