check job size before allocating from the log
check job size before allocating from the log

Coverity Scan defect 719429

wfxiang08/beanstalkd,wfxiang08/beanstalkd,handautsav/beanstalkd,LomoX-Offical/beanstalkd-win,potatosalad/beanstalkd,r3jack/beanstalkd,bmhatfield/beanstalkd,pinguo-xudianyang/beanstalkd,mickeyouyou/beanstalkd,LomoX-Offical/beanstalkd-win,mobliyishengyuan/beanstalkd,orangeholic/beanstalkd,naderman/beanstalkd,CompendiumSoftware/beanstalkd,mickeyouyou/beanstalkd,mobliyishengyuan/beanstalkd,potatosalad/beanstalkd,PhillipMwaniki/beanstalkd,r3jack/beanstalkd,qbdsoft/beanstalkd,yetone/beanstalkd,JensRantil/beanstalkd,Qihoo360/beanstalkd-win,tdg5/beanstalkd,kr/beanstalkd,amyvmiwei/beanstalkd,handautsav/beanstalkd,yetone/beanstalkd,aidaima/beanstalkd,diditaxi/beanstalkd,PhillipMwaniki/beanstalkd,lzpfmh/beanstalkd,JensRantil/beanstalkd,kr/beanstalkd,davies/beanstalkd,naderman/beanstalkd,pinguo-xudianyang/beanstalkd,diditaxi/beanstalkd,orangeholic/beanstalkd,wyzssw/beanstalkd,ifduyue/beanstalkd,aidaima/beanstalkd,lzpfmh/beanstalkd,amyvmiwei/beanstalkd,bmhatfield/beanstalkd,CompendiumSoftware/beanstalkd,tdg5/beanstalkd,qbdsoft/beanstalkd,cgvarela/beanstalkd,naderman/beanstalkd,justintung/beanstalkd,justintung/beanstalkd,cgvarela/beanstalkd,wyzssw/beanstalkd,Qihoo360/beanstalkd-win,ifduyue/beanstalkd,davies/beanstalkd