问题调用栈：

(gdb) bt
#0  0x000000000068307c in rd_kafka_q_pop_serve (rkq=0x1ff31a0, timeout_ms=<optimized out>, version=version@entry=0, cb_type=cb_type@entry=RD_KAFKA_Q_CB_RETURN, callback=callback@entry=0x0, opaque=opaque@entry=0x0) at rdkafka_queue.c:373
#1  0x0000000000683130 in rd_kafka_q_pop (rkq=<optimized out>, timeout_ms=<optimized out>, version=version@entry=0) at rdkafka_queue.c:399
#2  0x000000000066abcf in rd_kafka_broker_ops_serve (rkb=rkb@entry=0x1ff28e0, timeout_ms=<optimized out>) at rdkafka_broker.c:2510
#3  0x000000000066ac84 in rd_kafka_broker_serve (rkb=rkb@entry=0x1ff28e0, abs_timeout=abs_timeout@entry=71168163411018) at rdkafka_broker.c:2532
#4  0x000000000066b157 in rd_kafka_broker_ua_idle (rkb=rkb@entry=0x1ff28e0, timeout_ms=<optimized out>, timeout_ms@entry=-1) at rdkafka_broker.c:2617
#5  0x000000000066c796 in rd_kafka_broker_thread_main (arg=arg@entry=0x1ff28e0) at rdkafka_broker.c:3571
#6  0x00000000006b8d87 in _thrd_wrapper_function (aArg=<optimized out>) at tinycthread.c:583
#7  0x00007f80a07e1eb5 in start_thread () from /lib64/libpthread.so.0
#8  0x00007f80a05098fd in clone () from /lib64/libc.so.6

相关代码（rd_kafka_q_pop）：

rd_kafka_op_t *rd_kafka_q_pop (rd_kafka_q_t *rkq, int timeout_ms,int32_t version) {return rd_kafka_q_pop_serve(rkq, timeout_ms, version,RD_KAFKA_Q_CB_RETURN,NULL, NULL);
}

通过 gdb 观察到 timeout_ms 值为 1，也就是 1 毫秒，这是导致 cpu 百分百的原因：

(gdb) f 1
#1  0x0000000000683130 in rd_kafka_q_pop (rkq=<optimized out>, timeout_ms=<optimized out>, version=version@entry=0) at rdkafka_queue.c:399
399     in rdkafka_queue.c
(gdb) info args
rkq = <optimized out>
timeout_ms = <optimized out>
version = 0
(gdb) info reg
rax            0x0      0
rbx            0x0      0
rcx            0x64ab3c08       1688943624
rdx            0x7f7f537b4240   140184838160960
rsi            0x1ff31a0        33501600
rdi            0x1ff31c8        33501640
rbp            0x1ff28e0        0x1ff28e0
rsp            0x7f7f537b4288   0x7f7f537b4288
r8             0x7      7
r9             0x4748105a       1195905114
r10            0x7b     123
r11            0x1da063a5132567 8339124156310887
r12            0x7f7f537b42f0   140184838161136
r13            0x40ba2119744a   71168163411018
r14            0x0      0
r15            0x4      4
rip            0x683130 0x683130 <rd_kafka_q_serve>
eflags         0x246    [ PF ZF IF ]
cs             0x33     51
ss             0x2b     43
ds             0x0      0
es             0x0      0
fs             0x0      0
gs             0x0      0
(gdb) p *(rd_kafka_q_t*)0x1ff31c8
$1 = {rkq_lock = {__data = {__lock = 0, __count = 4289904, __owner = 2144952, __nusers = 0, __kind = 2144952, __spins = 0, __elision = 0, __list = {__prev = 0x20bab8, __next = 0x1ff31a0}}, __size = "\000\000\000\000puA\000\270\272 \000\000\000\000\000\270\272 \000\000\000\000\000\270\272 \000\000\000\000\000\240\061\377\001\000\000\000", __align = 18424997382979584}, rkq_cond = {__data = {__lock = 0, __futex = 0, __total_seq = 0, __wakeup_seq = 0, __woken_seq = 33501696, __mutex = 0x0, __nwaiters = 0, __broadcast_seq = 0}, __size = '\000' <repeats 25 times>, "\062\377\001", '\000' <repeats 19 times>, __align = 0}, rkq_fwdq = 0x300000001, rkq_q = {tqh_first = 0x1ff1930, tqh_last = 0x0}, rkq_qlen = 0, rkq_qsize = 0, rkq_refcnt = 9087760, rkq_flags = 0, rkq_rk = 0x0, rkq_qio = 0x261, rkq_serve = 0x23, rkq_opaque = 0x0, rkq_name = 0x1 <Address 0x1 out of bounds>}
(gdb) p *(int*)0x1ff31a0
$2 = 1

继续跟踪，问题发生在函数 cnd_timedwait_abs：

(gdb) b cnd_timedwait_abs
Breakpoint 1 at 0x6b92c0: file tinycthread_extra.c, line 95.
(gdb) c
Continuing.Breakpoint 1, cnd_timedwait_abs (cnd=cnd@entry=0x1ff31c8, mtx=mtx@entry=0x1ff31a0, tspec=tspec@entry=0x7f7f537b4240) at tinycthread_extra.c:95
95      tinycthread_extra.c: No such file or directory.
(gdb) p *tspec
$3 = {tv_sec = 1688943624, tv_nsec = 1000000000}

函数 cnd_timedwait_abs 源码：

int cnd_timedwait_abs (cnd_t *cnd, mtx_t *mtx, const struct timespec *tspec) {if (tspec->tv_sec == RD_POLL_INFINITE)return cnd_wait(cnd, mtx);else if (tspec->tv_sec == RD_POLL_NOWAIT)return thrd_timedout;return cnd_timedwait(cnd, mtx, tspec); // 走这里来了
}

底层调用的是 Posix 的 pthread_cond_timedwait 函数：

#include <pthread.h>int pthread_cond_timedwait(pthread_cond_t *restrict cond,pthread_mutex_t *restrict mutex,const struct timespec *restrict abstime);

函数 pthread_cond_timedwait 的参数 abstime 是个绝对时间，不是相对时间。初始化如下：

rd_kafka_op_t *rd_kafka_q_pop_serve (rd_kafka_q_t *rkq, int timeout_ms,int32_t version,rd_kafka_q_cb_type_t cb_type,rd_kafka_q_serve_cb_t *callback,void *opaque) {struct timespec timeout_tspec;rd_timeout_init_timespec(&timeout_tspec, timeout_ms);if (cnd_timedwait_abs(&rkq->rkq_cond, &rkq->rkq_lock, &timeout_tspec) == thrd_timedout) {mtx_unlock(&rkq->rkq_lock);}
}static RD_INLINE void rd_timeout_init_timespec (struct timespec *tspec, int timeout_ms) {if (timeout_ms == RD_POLL_INFINITE ||timeout_ms == RD_POLL_NOWAIT) {tspec->tv_sec = timeout_ms;tspec->tv_nsec = 0;} else {timespec_get(tspec, TIME_UTC); // 这里tspec->tv_sec  += timeout_ms / 1000;tspec->tv_nsec += (timeout_ms % 1000) * 1000000;if (tspec->tv_nsec > 1000000000) {tspec->tv_nsec -= 1000000000;tspec->tv_sec++;}}
}

函数 timespec_get：

/* If TIME_UTC is missing, provide it and provide a wrapper fortimespec_get. */
#ifndef TIME_UTC
#define TIME_UTC 1
#define _TTHREAD_EMULATE_TIMESPEC_GET_int _tthread_timespec_get(struct timespec *ts, int base);
#define timespec_get _tthread_timespec_get
#endif#if defined(_TTHREAD_EMULATE_TIMESPEC_GET_)
int _tthread_timespec_get(struct timespec *ts, int base)
{
#if defined(_TTHREAD_WIN32_)struct _timeb tb;
#elif !defined(CLOCK_REALTIME)struct timeval tv;
#endifif (base != TIME_UTC) // 约束为 UTC，即世界统一时间{return 0;}#if defined(_TTHREAD_WIN32_)_ftime_s(&tb);ts->tv_sec = (time_t)tb.time;ts->tv_nsec = 1000000L * (long)tb.millitm;
#elif defined(CLOCK_REALTIME)base = (clock_gettime(CLOCK_REALTIME, ts) == 0) ? base : 0;
#elsegettimeofday(&tv, NULL);ts->tv_sec = (time_t)tv.tv_sec;ts->tv_nsec = 1000L * (long)tv.tv_usec;
#endifreturn base;
}
#endif /* _TTHREAD_EMULATE_TIMESPEC_GET_ */

回过头看函数 cnd_timedwait_abs 的参数 tspec 的值：

(gdb) p *tspec
$3 = {tv_sec = 1688943624, tv_nsec = 1000000000}

将 tv_sec 转为可读的值：

时间戳（秒）	1688943624
ISO 8601	2023-07-09T23:00:24.000Z
日期时间（UTC）	2023-07-09 23:00:24
日期时间（本地）	2023-07-10 07:00:24

而本地的实际时间为：

# date +'%Y-%m-%d %H:%M:%S'
2023-07-13 16:15:27# date +'%s'
1689236277# expr 1689236277 - 1688943624
292653
# expr 292653 / 3600
81

很明显 tspec 不对，。

准备进一步分析时，遇到 gdb 的 bug 了：

(gdb) b gettimeofday
Breakpoint 1 at 0x7fddd8ba9650 (2 locations)
(gdb) b clock_gettime
Breakpoint 2 at gnu-indirect-function resolver at 0x7fddd8c08800 (3 locations)
(gdb) c
Continuing.
../../gdb/elfread.c:1052: internal-error: elf_gnu_ifunc_resolver_return_stop: Assertion `b->loc->next == NULL' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)

进一步验证是发生在 clock_gettime，单独断点 gettimeofday 没有问题，而且不会进入 gettimeofday。

$ man clock_gettimeclock_getres(), clock_gettime(), clock_settime():_POSIX_C_SOURCE >= 199309L#  ifdef __USE_POSIX199309
/* Identifier for system-wide realtime clock.  */
#   define CLOCK_REALTIME

找了个正常的，查看：

(gdb) p timeout_tspec
$2 = {tv_sec = 1689237800, tv_nsec = 687268217}# expr 1689237800 - 1688943624
294176
# expr 294176 / 3600
81

暂时怀疑 clock_gettime 调用出问题了，实现在最新的代码中没有变化：https://github.com/confluentinc/librdkafka/blob/master/src/tinycthread.c。