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- // 测试mktime和localtime_r性能及优化方法
- //
- // 编译方法:g++ -g -o x x.cpp或g++ -O2 -o x x.cpp,两种编译方式性能基本相同。
- //
- // 结论:
- // 1) 环境变量TZ和isdst均不影响localtime_r的性能(第一次调用了除外)
- // 2) 环境变量TZ严重影响localtime的性能
- // 3) 环境变量TZ和isdst均会严重影响mktime的性能
- // *4) 注意mktime的参数即是输入参数也是输出参数,它会修改isdst值
- // *5) 另外需要注意localtime_r为非信号安全函数,
- // 不能在信号处理过程中调用,否则可能发生死锁等问题
- //
- // 64位机器性能数据(与32位CPU不同):
- /*
- $ ./x 1000000
- test: localtime ...
- TZ is NULL: 2457ms
- TZ is empty: 172ms
- TZ is Asia/Shanghai: 173ms
-
- test: localtime_r ...
- TZ is NULL and isdst=1: 125ms
- TZ is NULL and isdst=0: 125ms
- TZ is NULL and isdst=-1: 125ms
- TZ is NULL and isdst undefined: 125ms
- TZ is empty and isdst=1: 125ms
- TZ is empty and isdst=0: 125ms
- TZ is empty and isdst=-1: 125ms
- TZ is empty and isdst undefined: 127ms
- TZ is Asia/Shanghai and isdst=1: 126ms
- TZ is Asia/Shanghai and isdst=0: 125ms
- TZ is Asia/Shanghai and isdst=-1: 125ms
- TZ is Asia/Shanghai and isdst undefined: 125ms
-
- test: mktime ...
- TZ is NULL and isdst=1: 635841ms
- TZ is NULL and isdst=0: 2583ms
- TZ is NULL and isdst=-1: 2596ms
- TZ is NULL and isdst undefined: 2579ms
- TZ is empty and isdst=1: 122377ms
- TZ is empty and isdst=0: 229ms
- TZ is empty and isdst=-1: 230ms
- TZ is empty and isdst undefined: 229ms
- TZ is Asia/Shanghai and isdst=1: 122536ms
- TZ is Asia/Shanghai and isdst=0: 228ms
- TZ is Asia/Shanghai and isdst=-1: 230ms
- TZ is Asia/Shanghai and isdst undefined: 228ms
- */
-
- // 32位机器性能数据(与64位CPU不同):
- /*
- $ ./x 1000000
- test: localtime ...
- TZ is NULL: 1445ms
- TZ is empty: 252ms
- TZ is Asia/Shanghai: 252ms
-
- test: localtime_r ...
- TZ is NULL and isdst=1: 161ms
- TZ is NULL and isdst=0: 160ms
- TZ is NULL and isdst=-1: 161ms
- TZ is NULL and isdst undefined: 161ms
- TZ is empty and isdst=1: 160ms
- TZ is empty and isdst=0: 161ms
- TZ is empty and isdst=-1: 161ms
- TZ is empty and isdst undefined: 161ms
- TZ is Asia/Shanghai and isdst=1: 161ms
- TZ is Asia/Shanghai and isdst=0: 161ms
- TZ is Asia/Shanghai and isdst=-1: 161ms
- TZ is Asia/Shanghai and isdst undefined: 161ms
-
- test: mktime ...
- TZ is NULL and isdst=1: 199375ms
- TZ is NULL and isdst=0: 1488ms
- TZ is NULL and isdst=-1: 1483ms
- TZ is NULL and isdst undefined: 1497ms
- TZ is empty and isdst=1: 161057ms
- TZ is empty and isdst=0: 325ms
- TZ is empty and isdst=-1: 328ms
- TZ is empty and isdst undefined: 326ms
- TZ is Asia/Shanghai and isdst=1: 161558ms
- TZ is Asia/Shanghai and isdst=0: 321ms
- TZ is Asia/Shanghai and isdst=-1: 335ms
- TZ is Asia/Shanghai and isdst undefined: 328ms
- */
- // localtime_r相关源代码:
- /*
- // The C Standard says that localtime and gmtime return the same pointer.
- struct tm _tmbuf; // 全局变量
-
- struct tm * __localtime_r (t, tp)
- const time_t *t;
- struct tm *tp;
- {
- return __tz_convert (t, 1, tp);
- }
-
- // 非线程安全版本,用到了全局变量_tmbuf
- struct tm * localtime(t)
- const time_t *t;
- {
- return __tz_convert (t, 1, &_tmbuf);
- }
-
- struct tm * __tz_convert (const time_t *timer, int use_localtime, struct tm *tp)
- {
- 。。。
- // 信号处理函数中调用非信号安全函数,可能造成死锁的地方
- __libc_lock_lock (tzset_lock);
-
- // localtime_r未用到_tmbuf,只是localtime使用它!!!
- // 因此对于localtime_r,传递给tzset_internal的第一个参数总是为0(tp != &_tmpbuf),
- // 而对于localtime,它传递给tzset_internal的第一个参数总是为1
- tzset_internal (tp == &_tmbuf && use_localtime, 1);
- 。。。
- }
-
- // 决定性能的函数,原因是可能涉及文件操作,
- // 因此要想提升性能,则应当想办法避免操作文件!!!
- static void internal_function
- tzset_internal (always, explicit)
- int always;
- int explicit;
- {
- static int is_initialized; // 静态变量
- const char *tz;
-
- // 对于mktime,参数always值总是为1
- // 对于localtime,参数always值总是为1
- // 对于localtime_r,参数always值总是为0
- if (is_initialized && !always)
- return; // 对于localtime_r第一次调用后,后续都在这里直接返回!
- is_initialized = 1;
-
- tz = getenv ("TZ");
- if (tz == NULL && !explicit)
- tz = TZDEFAULT;
- if (tz && *tz == '\0')
- tz = "Universal";
- if (tz && *tz == ':')
- ++tz;
-
- // 如果不设置环境变量TZ,则下面这个if语句总是不成立!!!
- // 因此只有设置了环境变量TZ,才有可能在这里直接返回而不进入读文件操作__tzfile_read
- if (old_tz != NULL && tz != NULL && strcmp (tz, old_tz) == 0)
- return; // 在这里返回则可以避免走到文件操作__tzfile_read
- if (tz == NULL)
- tz = TZDEFAULT;
-
- tz_rules[0].name = NULL;
- tz_rules[1].name = NULL;
-
- // Save the value of `tz'.
- free (old_tz);
- old_tz = tz ? __strdup (tz) : NULL;
-
- // 读文件,性能慢的原因
- __tzfile_read (tz, 0, NULL); // Try to read a data file.
- if (__use_tzfile)
- return;
- 。。。
- }
- */
- // mktime相关源代码:
- /*
- time_t mktime (struct tm *tp)
- {
- #ifdef _LIBC
- // POSIX.1 8.1.1 requires that whenever mktime() is called, the
- // time zone names contained in the external variable 'tzname' shall
- // be set as if the tzset() function had been called.
- __tzset ();
- #endif
-
- // __mktime_internal会调用localtime_r,
- // isdst的取值在这里会严重影响到mktime的性能
- return __mktime_internal (tp, __localtime_r, &localtime_offset);
- }
-
- void __tzset (void)
- {
- __libc_lock_lock (tzset_lock);
-
- // 和localtime_r一样也会调用tzset_internal
- tzset_internal (1, 1);
-
- if (!__use_tzfile)
- {
- // Set `tzname'.
- __tzname[0] = (char *) tz_rules[0].name;
- __tzname[1] = (char *) tz_rules[1].name;
- }
-
- __libc_lock_unlock (tzset_lock);
- }
- */
- #include stdlib.h>
- #include stdio.h>
- #include string.h>
- #include sys/time.h>
- #include time.h>
-
- static void test_localtime(int M); // 测试localtime性能
- static void test_localtime_r(int M); // 测试localtime_r性能
- static void test_mktime(int M); // 测试mktime性能
-
- int main(int argc, char* argv[])
- {
- const int M = (argc2)? 1000000: atoi(argv[1]);
-
- test_localtime(M);
- printf("\n");
- test_localtime_r(M);
- printf("\n");
- test_mktime(M);
-
- return 0;
- }
-
- // test_localtime
- void test_localtime(int M)
- {
- int i;
- time_t now = time(NULL);
- struct timeval tv1, tv2;
-
- printf("test: localtime ...\n");
- unsetenv("TZ");
-
- // test1
- {
- struct tm* result1;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- result1 = localtime(&now);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is NULL: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- setenv("TZ", "", 0);
-
- // test2
- {
- struct tm* result2;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- result2 = localtime(&now);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is empty: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- setenv("TZ", "Asia/Shanghai", 0);
-
- // test3
- {
- struct tm* result3;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- result3 = localtime(&now);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is Asia/Shanghai: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
- }
-
- // test_localtime_r
- void test_localtime_r(int M)
- {
- int i;
- time_t now = time(NULL);
- struct timeval tv1, tv2;
-
- printf("test: localtime_r ...\n");
- unsetenv("TZ");
-
- // test1
- {
- struct tm result1;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result1_;
- memcpy(&result1_, &result1, sizeof(result1_));
- result1_.tm_isdst = 1;
- localtime_r(&now, &result1_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is NULL and isdst=1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test2
- {
- struct tm result2;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result2_;
- memcpy(&result2_, &result2, sizeof(result2_));
- result2_.tm_isdst = 0;
- localtime_r(&now, &result2_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is NULL and isdst=0: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test3
- {
- struct tm result3;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result3_;
- memcpy(&result3_, &result3, sizeof(result3_));
- result3_.tm_isdst = -1;
- localtime_r(&now, &result3_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is NULL and isdst=-1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test4
- {
- struct tm result4;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result4_;
- memcpy(&result4_, &result4, sizeof(result4_));
- localtime_r(&now, &result4_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is NULL and isdst undefined: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- setenv("TZ", "", 0);
-
- // test5
- {
- struct tm result5;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result5_;
- memcpy(&result5_, &result5, sizeof(result5_));
- result5_.tm_isdst = 1;
- localtime_r(&now, &result5_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is empty and isdst=1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test6
- {
- struct tm result6;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result6_;
- memcpy(&result6_, &result6, sizeof(result6_));
- result6_.tm_isdst = 0;
- localtime_r(&now, &result6_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is empty and isdst=0: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test7
- {
- struct tm result7;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result7_;
- memcpy(&result7_, &result7, sizeof(result7_));
- result7_.tm_isdst = -1;
- localtime_r(&now, &result7_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is empty and isdst=-1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test8
- {
- struct tm result8;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result8_;
- memcpy(&result8_, &result8, sizeof(result8_));
- result8_.tm_isdst = -1;
- localtime_r(&now, &result8_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is empty and isdst undefined: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- setenv("TZ", "Asia/Shanghai", 0);
-
- // test9
- {
- struct tm result9;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result9_;
- memcpy(&result9_, &result9, sizeof(result9_));
- result9_.tm_isdst = 1;
- localtime_r(&now, &result9_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is Asia/Shanghai and isdst=1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test10
- {
- struct tm result10;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result10_;
- memcpy(&result10_, &result10, sizeof(result10_));
- result10_.tm_isdst = 0;
- localtime_r(&now, &result10_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is Asia/Shanghai and isdst=0: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test11
- {
- struct tm result11;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result11_;
- memcpy(&result11_, &result11, sizeof(result11_));
- result11_.tm_isdst = -1;
- localtime_r(&now, &result11_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is Asia/Shanghai and isdst=-1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test12
- {
- struct tm result12;
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result12_;
- memcpy(&result12_, &result12, sizeof(result12_));
- localtime_r(&now, &result12_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is Asia/Shanghai and isdst undefined: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
- }
-
- // test_mktime
- void test_mktime(int M)
- {
- int i;
- time_t now = time(NULL);
- struct timeval tv1, tv2;
-
- printf("test: mktime ...\n");
- unsetenv("TZ");
-
- // test1
- {
- struct tm result1;
- localtime_r(&now, &result1);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result1_;
- memcpy(&result1_, &result1, sizeof(result1_));
- result1_.tm_isdst = 1;
- mktime(&result1_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is NULL and isdst=1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test2
- {
- struct tm result2;
- localtime_r(&now, &result2);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result2_;
- memcpy(&result2_, &result2, sizeof(result2_));
- result2_.tm_isdst = 0;
- mktime(&result2_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is NULL and isdst=0: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test3
- {
- struct tm result3;
- localtime_r(&now, &result3);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result3_;
- memcpy(&result3_, &result3, sizeof(result3_));
- result3_.tm_isdst = -1;
- mktime(&result3_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is NULL and isdst=-1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test4
- {
- struct tm result4;
- localtime_r(&now, &result4);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result4_;
- memcpy(&result4_, &result4, sizeof(result4_));
- mktime(&result4_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is NULL and isdst undefined: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- setenv("TZ", "", 0);
-
- // test5
- {
- struct tm result5;
- localtime_r(&now, &result5);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result5_;
- memcpy(&result5_, &result5, sizeof(result5_));
- result5_.tm_isdst = 1;
- mktime(&result5_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is empty and isdst=1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test6
- {
- struct tm result6;
- localtime_r(&now, &result6);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result6_;
- memcpy(&result6_, &result6, sizeof(result6_));
- result6_.tm_isdst = 0;
- mktime(&result6_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is empty and isdst=0: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test7
- {
- struct tm result7;
- localtime_r(&now, &result7);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result7_;
- memcpy(&result7_, &result7, sizeof(result7_));
- result7_.tm_isdst = -1;
- mktime(&result7_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is empty and isdst=-1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test8
- {
- struct tm result8;
- localtime_r(&now, &result8);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result8_;
- memcpy(&result8_, &result8, sizeof(result8_));
- mktime(&result8_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is empty and isdst undefined: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- setenv("TZ", "Asia/Shanghai", 0);
-
- // test9
- {
- struct tm result9;
- localtime_r(&now, &result9);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result9_;
- memcpy(&result9_, &result9, sizeof(result9_));
- result9_.tm_isdst = 1;
- mktime(&result9_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is Asia/Shanghai and isdst=1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test10
- {
- struct tm result10;
- localtime_r(&now, &result10);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result10_;
- memcpy(&result10_, &result10, sizeof(result10_));
- result10_.tm_isdst = 0;
- mktime(&result10_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is Asia/Shanghai and isdst=0: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test11
- {
- struct tm result11;
- localtime_r(&now, &result11);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result11_;
- memcpy(&result11_, &result11, sizeof(result11_));
- result11_.tm_isdst = -1;
- mktime(&result11_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is Asia/Shanghai and isdst=-1: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
-
- // test12
- {
- struct tm result12;
- localtime_r(&now, &result12);
- gettimeofday(&tv1, NULL);
- for (i=0; iM; ++i)
- {
- struct tm result12_;
- memcpy(&result12_, &result12, sizeof(result12_));
- mktime(&result12_);
- }
- gettimeofday(&tv2, NULL);
- printf("TZ is Asia/Shanghai and isdst undefined: %ums\n", (tv2.tv_sec-tv1.tv_sec)*1000 + (tv2.tv_usec-tv1.tv_usec)/1000);
- }
- }