用系统调用signal()让父进程捕捉键盘上来的中断信号（按Ctrl-C键）；当捕捉到中断信号后，父进程用系统调用kill()向两个子进程发出信号，子进程捕捉到信号后分别输出下列信息后终止： Child Process 1 is Killed by Parent! Child Process 2 is Killed by Parent! 父进程等待两个子进程终止后，输出如下的信息后终止： Parent Process is Killed!
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001309s ]
SELECT `a`.`aid`,`a`.`title`,`a`.`create_time`,`m`.`username` FROM `jrk_downrecords` `a` INNER JOIN `jrk_member` `m` ON `a`.`uid`=`m`.`id` WHERE `a`.`status` = 1 GROUP BY `a`.`aid` ORDER BY `a`.`create_time` DESC LIMIT 10 [ RunTime:0.090831s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001233s ]
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SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001230s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003631s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.001090s ]
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SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.016430s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001431s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 521843 [ RunTime:0.001401s ]
