Error when sending _bulk_docs request with large number of docs

After increasing kNumDocs and kNumPros to 1000, in test "Pull deltas from Collection SG", I got following errors and warning,

>>> Pull deltas from Collection SG

        — Rev-trees

13:45:01.178313| [TLS] ERROR: mbedTLS(C): mbedtls_ssl_flush_output() returned -80 (-0x0050)
13:45:01.178560| [TLS] ERROR: mbedTLS(C): mbedtls_ssl_write_record() returned -80 (-0x0050)
13:45:01.181414| [TLS] ERROR: mbedTLS(C): mbedtls_ssl_send_alert_message() returned -80 (-0x0050)
13:45:06.858528| [WS] WARNING: ClientSocket got POSIX error 35 "Resource temporarily unavailable"

13:45:06.932644| INFO: -------- PASS #1: Repopulating local db --------
13:45:42.558324| INFO: -------- PASS #1: Pull took 23.476 sec (43 docs/sec) --------
13:45:42.627063| INFO: -------- PASS #2: Repopulating local db --------
13:46:13.080143| INFO: -------- PASS #2: Pull took 22.180 sec (45 docs/sec) --------
13:46:13.124751| INFO: -------- PASS #3: Repopulating local db --------
13:46:43.379360| INFO: -------- PASS #3: Pull took 22.193 sec (45 docs/sec) --------
13:46:43.420158| INFO: -------- 22.180 sec with deltas, 22.193 sec without; 1.00x speed

    [161.212 sec]

=======================================================================================================================

All tests passed (7063 assertions in 1 test case)

--------------- cut here ---------------

Notice that all test assertions are passed.