I haven't updated in a few weeks, so let me know if this is already fixed?

./rdkafka_performance -C -t EMSNALOGS -p 0 -b masked.com:5757 -B 1 -o beginning

% Using random seed 1395109032
rdkafka_performance: rdkafka_broker.c:313: rd_kafka_broker_fail: Assertion `pthread_self() == rkb->rkb_thread' failed.
Aborted (core dumped)

Loaded symbols for /lib/modules/2.6.32-220.13.1.el6.x86_64/vdso/vdso.so
Core was generated by `./rdkafka_performance -C -t EMSNALOGS -p 0 -b masked'.
Program terminated with signal 6, Aborted.
#0 0x0000003d23232885 in raise () from /lib64/libc.so.6

Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.47.el6_2.9.x86_64 zlib-1.2.3-27.el6.x86_64
(gdb) where
#0 0x0000003d23232885 in raise () from /lib64/libc.so.6
#1 0x0000003d23234065 in abort () from /lib64/libc.so.6
#2 0x0000003d2322b9fe in __assert_fail_base () from /lib64/libc.so.6
#3 0x0000003d2322bac0 in __assert_fail () from /lib64/libc.so.6
#4 0x000000000040c744 in rd_kafka_broker_fail (rkb=0xc9d740, err=RD_KAFKA_RESP_ERR__DESTROY, fmt=0x0) at rdkafka_broker.c:313
#5 0x000000000040e910 in rd_kafka_broker_thread_main (arg=0xc9d740) at rdkafka_broker.c:3282
#6 0x0000003d23a077f1 in start_thread () from /lib64/libpthread.so.0
#7 0x0000003d232e5ccd in clone () from /lib64/libc.so.6