cpp_macos_opt_native: ClientLbEnd2endTest.RoundRobinSingleReconnect is flaky #15500
Description
Look like this is failing >10% of runs.
Recent failures on master:
https://source.cloud.google.com/results/invocations/55dd633b-a709-4c18-8213-455711f3f7d0/targets/github%2Fgrpc%2Fcpp_macos_opt_native/tests
https://source.cloud.google.com/results/invocations/c69a23ac-e4a4-4fca-b9cd-ed085797e92d/targets/github%2Fgrpc%2Fcpp_macos_opt_native/tests
[ RUN ] ClientLbEnd2endTest.RoundRobinSingleReconnect
I0520 11:39:20.218761000 140735816057792 client_lb_end2end_test.cc:240] starting server on port 1419
I0520 11:39:20.218912000 123145447247872 server_builder.cc:269] Synchronous server. Num CQs: 1, Min pollers: 1, Max Pollers: 2, CQ timeout (msec): 10000
I0520 11:39:20.219988000 140735816057792 client_lb_end2end_test.cc:248] server startup complete
I0520 11:39:20.222152000 140735816057792 client_lb_end2end_test.cc:240] starting server on port 21785
I0520 11:39:20.222285000 123145448321024 server_builder.cc:269] Synchronous server. Num CQs: 1, Min pollers: 1, Max Pollers: 2, CQ timeout (msec): 10000
I0520 11:39:20.223324000 140735816057792 client_lb_end2end_test.cc:248] server startup complete
I0520 11:39:20.225823000 140735816057792 client_lb_end2end_test.cc:240] starting server on port 7950
I0520 11:39:20.225906000 123145449394176 server_builder.cc:269] Synchronous server. Num CQs: 1, Min pollers: 1, Max Pollers: 2, CQ timeout (msec): 10000
I0520 11:39:20.226922000 140735816057792 client_lb_end2end_test.cc:248] server startup complete
I0520 11:39:20.227770000 140735816057792 subchannel.cc:608] New connected subchannel at 0x7faf6b204ee0 for subchannel 0x7faf6b202fb0
I0520 11:39:20.227800000 140735816057792 subchannel.cc:608] New connected subchannel at 0x7faf6b2032b0 for subchannel 0x7faf6b203a10
I0520 11:39:20.228076000 140735816057792 subchannel.cc:608] New connected subchannel at 0x7faf6b202a10 for subchannel 0x7faf6b204470
I0520 11:39:20.231193000 123145446711296 subchannel.cc:646] Connect failed: {"created":"@1526841560.231161000","description":"Failed to connect to remote host: OS Error","errno":61,"file":"src/core/lib/iomgr/tcp_client_posix.cc","file_line":202,"os_error":"Connection refused","syscall":"connect","target_address":"ipv4:127.0.0.1:1419"}
I0520 11:39:20.231235000 123145446711296 subchannel.cc:470] Subchannel 0x7faf6b202fb0: Retry in 999 milliseconds
I0520 11:39:20.237777000 140735816057792 client_lb_end2end_test.cc:240] starting server on port 1419
I0520 11:39:20.237900000 123145447247872 server_builder.cc:269] Synchronous server. Num CQs: 1, Min pollers: 1, Max Pollers: 2, CQ timeout (msec): 10000
I0520 11:39:20.239032000 140735816057792 client_lb_end2end_test.cc:248] server startup complete
I0520 11:39:21.627715000 123145450467328 subchannel.cc:425] Failed to connect to channel, retrying
I0520 11:39:21.990911000 123145450467328 subchannel.cc:608] New connected subchannel at 0x7faf69700030 for subchannel 0x7faf6b202fb0
*******************************
Caught signal SIGABRT
no backtrace
Command terminated abnormally.