Delay reading stdout from disk until process terminates
Delay reading stdout from disk until process terminates

The current code reads the stdout of each running process each time it
goes through a reap() iteration, and throws it away if the process is
still running.

On Windows, where we poll for completion every 100ms, I expect this is
having a serious impact on Jenkins performance, especially for noisier
tests.

kpayson64/grpc,ejona86/grpc,podsvirov/grpc,apolcyn/grpc,royalharsh/grpc,muxi/grpc,adelez/grpc,royalharsh/grpc,simonkuang/grpc,vjpai/grpc,7anner/grpc,yongni/grpc,a-veitch/grpc,VcamX/grpc,thinkerou/grpc,chrisdunelm/grpc,nicolasnoble/grpc,grpc/grpc,ejona86/grpc,wcevans/grpc,matt-kwong/grpc,firebase/grpc,hstefan/grpc,ctiller/grpc,dklempner/grpc,mehrdada/grpc,vjpai/grpc,soltanmm-google/grpc,msiedlarek/grpc,makdharma/grpc,ctiller/grpc,perumaalgoog/grpc,vsco/grpc,thinkerou/grpc,thunderboltsid/grpc,kumaralokgithub/grpc,soltanmm/grpc,nicolasnoble/grpc,adelez/grpc,geffzhang/grpc,donnadionne/grpc,a-veitch/grpc,donnadionne/grpc,ctiller/grpc,adelez/grpc,yang-g/grpc,infinit/grpc,leifurhauks/grpc,Vizerai/grpc,goldenbull/grpc,grpc/grpc,infinit/grpc,yongni/grpc,kskalski/grpc,dklempner/grpc,perumaalgoog/grpc,dgquintas/grpc,arkmaxim/grpc,carl-mastrangelo/grpc,tengyifei/grpc,daniel-j-born/grpc,muxi/grpc,fuchsia-mirror/third_party-grpc,pszemus/grpc,simonkuang/grpc,malexzx/grpc,Vizerai/grpc,miselin/grpc,LuminateWireless/grpc,mehrdada/grpc,ipylypiv/grpc,soltanmm/grpc,yongni/grpc,Crevil/grpc,kriswuollett/grpc,ipylypiv/grpc,a11r/grpc,bogdandrutu/grpc,7anner/grpc,yugui/grpc,fuchsia-mirror/third_party-grpc,a11r/grpc,rjshade/grpc,kpayson64/grpc,y-zeng/grpc,thunderboltsid/grpc,ncteisen/grpc,pmarks-net/grpc,royalharsh/grpc,Vizerai/grpc,dgquintas/grpc,royalharsh/grpc,muxi/grpc,VcamX/grpc,zhimingxie/grpc,andrewpollock/grpc,fuchsia-mirror/third_party-grpc,quizlet/grpc,geffzhang/grpc,VcamX/grpc,tamihiro/grpc,soltanmm/grpc,mehrdada/grpc,PeterFaiman/ruby-grpc-minimal,nicolasnoble/grpc,carl-mastrangelo/grpc,ejona86/grpc,podsvirov/grpc,hstefan/grpc,dklempner/grpc,PeterFaiman/ruby-grpc-minimal,kpayson64/grpc,greasypizza/grpc,vsco/grpc,philcleveland/grpc,grpc/grpc,perumaalgoog/grpc,PeterFaiman/ruby-grpc-minimal,royalharsh/grpc,arkmaxim/grpc,jboeuf/grpc,MakMukhi/grpc,donnadionne/grpc,a-veitch/grpc,arkmaxim/grpc,nicolasnoble/grpc,greasypizza/grpc,greasypizza/grpc,msmania/grpc,ananthonline/grpc,infinit/grpc,simonkuang/grpc,yugui/grpc,Vizerai/grpc,andrewpollock/grpc,soltanmm-google/grpc,makdharma/grpc,Vizerai/grpc,Crevil/grpc,jtattermusch/grpc,ejona86/grpc,royalharsh/grpc,firebase/grpc,firebase/grpc,leifurhauks/grpc,andrewpollock/grpc,ananthonline/grpc,pszemus/grpc,bogdandrutu/grpc,zhimingxie/grpc,miselin/grpc,a11r/grpc,ctiller/grpc,thunderboltsid/grpc,ncteisen/grpc,ipylypiv/grpc,zhimingxie/grpc,malexzx/grpc,LuminateWireless/grpc,msmania/grpc,daniel-j-born/grpc,philcleveland/grpc,daniel-j-born/grpc,leifurhauks/grpc,donnadionne/grpc,hstefan/grpc,matt-kwong/grpc,chrisdunelm/grpc,msmania/grpc,arkmaxim/grpc,hstefan/grpc,kumaralokgithub/grpc,firebase/grpc,arkmaxim/grpc,dklempner/grpc,arkmaxim/grpc,msmania/grpc,Crevil/grpc,zhimingxie/grpc,ipylypiv/grpc,y-zeng/grpc,donnadionne/grpc,infinit/grpc,yang-g/grpc,kskalski/grpc,grani/grpc,tamihiro/grpc,tamihiro/grpc,kpayson64/grpc,pmarks-net/grpc,kriswuollett/grpc,stanley-cheung/grpc,kriswuollett/grpc,a11r/grpc,a-veitch/grpc,tengyifei/grpc,ppietrasa/grpc,podsvirov/grpc,PeterFaiman/ruby-grpc-minimal,goldenbull/grpc,tengyifei/grpc,fuchsia-mirror/third_party-grpc,simonkuang/grpc,pmarks-net/grpc,miselin/grpc,philcleveland/grpc,mehrdada/grpc,simonkuang/grpc,sreecha/grpc,VcamX/grpc,kumaralokgithub/grpc,sreecha/grpc,apolcyn/grpc,kumaralokgithub/grpc,ctiller/grpc,VcamX/grpc,kskalski/grpc,chrisdunelm/grpc,kskalski/grpc,PeterFaiman/ruby-grpc-minimal,kumaralokgithub/grpc,soltanmm-google/grpc,Crevil/grpc,malexzx/grpc,jtattermusch/grpc,wcevans/grpc,makdharma/grpc,msiedlarek/grpc,LuminateWireless/grpc,tamihiro/grpc,adelez/grpc,philcleveland/grpc,ctiller/grpc,grani/grpc,zhimingxie/grpc,baylabs/grpc,malexzx/grpc,geffzhang/grpc,podsvirov/grpc,muxi/grpc,Vizerai/grpc,pmarks-net/grpc,grpc/grpc,vjpai/grpc,PeterFaiman/ruby-grpc-minimal,pmarks-net/grpc,ncteisen/grpc,zhimingxie/grpc,apolcyn/grpc,muxi/grpc,ncteisen/grpc,firebase/grpc,deepaklukose/grpc,chrisdunelm/grpc,firebase/grpc,jtattermusch/grpc,pszemus/grpc,pszemus/grpc,thunderboltsid/grpc,jboeuf/grpc,greasypizza/grpc,grpc/grpc,vjpai/grpc,a-veitch/grpc,baylabs/grpc,7anner/grpc,jcanizales/grpc,tengyifei/grpc,leifurhauks/grpc,yang-g/grpc,kskalski/grpc,PeterFaiman/ruby-grpc-minimal,a-veitch/grpc,deepaklukose/grpc,miselin/grpc,wcevans/grpc,thinkerou/grpc,stanley-cheung/grpc,pmarks-net/grpc,stanley-cheung/grpc,muxi/grpc,tamihiro/grpc,wcevans/grpc,infinit/grpc,leifurhauks/grpc,bogdandrutu/grpc,podsvirov/grpc,hstefan/grpc,malexzx/grpc,murgatroid99/grpc,a11r/grpc,yugui/grpc,miselin/grpc,jtattermusch/grpc,ncteisen/grpc,perumaalgoog/grpc,yang-g/grpc,matt-kwong/grpc,vjpai/grpc,soltanmm/grpc,simonkuang/grpc,thunderboltsid/grpc,tamihiro/grpc,carl-mastrangelo/grpc,baylabs/grpc,MakMukhi/grpc,podsvirov/grpc,soltanmm/grpc,royalharsh/grpc,y-zeng/grpc,ppietrasa/grpc,soltanmm-google/grpc,podsvirov/grpc,VcamX/grpc,MakMukhi/grpc,hstefan/grpc,msmania/grpc,kpayson64/grpc,greasypizza/grpc,ejona86/grpc,kriswuollett/grpc,apolcyn/grpc,makdharma/grpc,VcamX/grpc,philcleveland/grpc,carl-mastrangelo/grpc,ctiller/grpc,infinit/grpc,sreecha/grpc,VcamX/grpc,7anner/grpc,stanley-cheung/grpc,jcanizales/grpc,quizlet/grpc,tamihiro/grpc,ananthonline/grpc,jtattermusch/grpc,murgatroid99/grpc,deepaklukose/grpc,philcleveland/grpc,pszemus/grpc,yongni/grpc,firebase/grpc,carl-mastrangelo/grpc,greasypizza/grpc,vsco/grpc,ctiller/grpc,muxi/grpc,vsco/grpc,vjpai/grpc,kpayson64/grpc,goldenbull/grpc,yongni/grpc,thinkerou/grpc,vjpai/grpc,pmarks-net/grpc,grani/grpc,geffzhang/grpc,soltanmm/grpc,Crevil/grpc,donnadionne/grpc,thunderboltsid/grpc,jcanizales/grpc,a-veitch/grpc,Vizerai/grpc,daniel-j-born/grpc,adelez/grpc,baylabs/grpc,soltanmm-google/grpc,donnadionne/grpc,Crevil/grpc,grani/grpc,dgquintas/grpc,muxi/grpc,ipylypiv/grpc,rjshade/grpc,dklempner/grpc,geffzhang/grpc,grpc/grpc,podsvirov/grpc,ncteisen/grpc,a11r/grpc,nicolasnoble/grpc,chrisdunelm/grpc,leifurhauks/grpc,grani/grpc,kumaralokgithub/grpc,yugui/grpc,yugui/grpc,fuchsia-mirror/third_party-grpc,perumaalgoog/grpc,msiedlarek/grpc,deepaklukose/grpc,ananthonline/grpc,zhimingxie/grpc,jtattermusch/grpc,soltanmm-google/grpc,vjpai/grpc,goldenbull/grpc,jcanizales/grpc,muxi/grpc,matt-kwong/grpc,tengyifei/grpc,hstefan/grpc,nicolasnoble/grpc,matt-kwong/grpc,miselin/grpc,MakMukhi/grpc,jboeuf/grpc,ipylypiv/grpc,matt-kwong/grpc,soltanmm/grpc,Vizerai/grpc,perumaalgoog/grpc,nicolasnoble/grpc,jboeuf/grpc,hstefan/grpc,makdharma/grpc,yongni/grpc,fuchsia-mirror/third_party-grpc,MakMukhi/grpc,jtattermusch/grpc,mehrdada/grpc,a11r/grpc,dgquintas/grpc,carl-mastrangelo/grpc,donnadionne/grpc,quizlet/grpc,kriswuollett/grpc,tengyifei/grpc,kpayson64/grpc,carl-mastrangelo/grpc,baylabs/grpc,ipylypiv/grpc,pmarks-net/grpc,MakMukhi/grpc,deepaklukose/grpc,thinkerou/grpc,msmania/grpc,vsco/grpc,andrewpollock/grpc,miselin/grpc,thinkerou/grpc,pszemus/grpc,nicolasnoble/grpc,simonkuang/grpc,baylabs/grpc,fuchsia-mirror/third_party-grpc,rjshade/grpc,jtattermusch/grpc,grani/grpc,greasypizza/grpc,ncteisen/grpc,jcanizales/grpc,donnadionne/grpc,grpc/grpc,royalharsh/grpc,grani/grpc,andrewpollock/grpc,yongni/grpc,kpayson64/grpc,ananthonline/grpc,vjpai/grpc,7anner/grpc,pszemus/grpc,apolcyn/grpc,sreecha/grpc,geffzhang/grpc,quizlet/grpc,carl-mastrangelo/grpc,soltanmm-google/grpc,soltanmm/grpc,murgatroid99/grpc,daniel-j-born/grpc,yongni/grpc,kriswuollett/grpc,andrewpollock/grpc,fuchsia-mirror/third_party-grpc,deepaklukose/grpc,kpayson64/grpc,bogdandrutu/grpc,ananthonline/grpc,makdharma/grpc,murgatroid99/grpc,a-veitch/grpc,chrisdunelm/grpc,muxi/grpc,kumaralokgithub/grpc,ncteisen/grpc,dgquintas/grpc,rjshade/grpc,quizlet/grpc,pszemus/grpc,bogdandrutu/grpc,apolcyn/grpc,grani/grpc,murgatroid99/grpc,goldenbull/grpc,sreecha/grpc,fuchsia-mirror/third_party-grpc,malexzx/grpc,jcanizales/grpc,ejona86/grpc,malexzx/grpc,matt-kwong/grpc,goldenbull/grpc,bogdandrutu/grpc,adelez/grpc,arkmaxim/grpc,kskalski/grpc,jboeuf/grpc,podsvirov/grpc,andrewpollock/grpc,andrewpollock/grpc,dgquintas/grpc,jboeuf/grpc,muxi/grpc,murgatroid99/grpc,daniel-j-born/grpc,jcanizales/grpc,pszemus/grpc,jboeuf/grpc,wcevans/grpc,bogdandrutu/grpc,daniel-j-born/grpc,tengyifei/grpc,ppietrasa/grpc,kskalski/grpc,ejona86/grpc,PeterFaiman/ruby-grpc-minimal,vjpai/grpc,tengyifei/grpc,stanley-cheung/grpc,LuminateWireless/grpc,carl-mastrangelo/grpc,baylabs/grpc,mehrdada/grpc,dklempner/grpc,yongni/grpc,ananthonline/grpc,carl-mastrangelo/grpc,rjshade/grpc,7anner/grpc,MakMukhi/grpc,ejona86/grpc,ppietrasa/grpc,goldenbull/grpc,a11r/grpc,a-veitch/grpc,arkmaxim/grpc,sreecha/grpc,deepaklukose/grpc,soltanmm-google/grpc,MakMukhi/grpc,quizlet/grpc,rjshade/grpc,dgquintas/grpc,ncteisen/grpc,deepaklukose/grpc,ipylypiv/grpc,quizlet/grpc,vjpai/grpc,miselin/grpc,rjshade/grpc,sreecha/grpc,ncteisen/grpc,VcamX/grpc,thinkerou/grpc,matt-kwong/grpc,chrisdunelm/grpc,firebase/grpc,wcevans/grpc,grpc/grpc,y-zeng/grpc,infinit/grpc,wcevans/grpc,chrisdunelm/grpc,quizlet/grpc,mehrdada/grpc,mehrdada/grpc,chrisdunelm/grpc,wcevans/grpc,grpc/grpc,msiedlarek/grpc,y-zeng/grpc,ppietrasa/grpc,makdharma/grpc,Vizerai/grpc,yang-g/grpc,ppietrasa/grpc,adelez/grpc,stanley-cheung/grpc,sreecha/grpc,malexzx/grpc,mehrdada/grpc,bogdandrutu/grpc,philcleveland/grpc,apolcyn/grpc,miselin/grpc,leifurhauks/grpc,LuminateWireless/grpc,sreecha/grpc,soltanmm/grpc,Vizerai/grpc,grpc/grpc,donnadionne/grpc,chrisdunelm/grpc,jtattermusch/grpc,Crevil/grpc,ncteisen/grpc,jtattermusch/grpc,perumaalgoog/grpc,vsco/grpc,grpc/grpc,LuminateWireless/grpc,stanley-cheung/grpc,hstefan/grpc,msiedlarek/grpc,kumaralokgithub/grpc,daniel-j-born/grpc,goldenbull/grpc,kskalski/grpc,ejona86/grpc,vsco/grpc,carl-mastrangelo/grpc,ppietrasa/grpc,7anner/grpc,leifurhauks/grpc,dklempner/grpc,thinkerou/grpc,pmarks-net/grpc,wcevans/grpc,msiedlarek/grpc,chrisdunelm/grpc,greasypizza/grpc,vjpai/grpc,arkmaxim/grpc,LuminateWireless/grpc,thinkerou/grpc,greasypizza/grpc,Vizerai/grpc,yugui/grpc,yang-g/grpc,goldenbull/grpc,vsco/grpc,sreecha/grpc,thinkerou/grpc,jboeuf/grpc,rjshade/grpc,bogdandrutu/grpc,adelez/grpc,kriswuollett/grpc,dklempner/grpc,ctiller/grpc,ejona86/grpc,7anner/grpc,ejona86/grpc,dgquintas/grpc,quizlet/grpc,ncteisen/grpc,muxi/grpc,infinit/grpc,dgquintas/grpc,y-zeng/grpc,ctiller/grpc,yugui/grpc,jtattermusch/grpc,geffzhang/grpc,thinkerou/grpc,tamihiro/grpc,geffzhang/grpc,ctiller/grpc,thunderboltsid/grpc,malexzx/grpc,msmania/grpc,stanley-cheung/grpc,zhimingxie/grpc,firebase/grpc,sreecha/grpc,stanley-cheung/grpc,yang-g/grpc,kpayson64/grpc,msmania/grpc,dklempner/grpc,yugui/grpc,pszemus/grpc,murgatroid99/grpc,zhimingxie/grpc,adelez/grpc,dgquintas/grpc,grani/grpc,Crevil/grpc,jboeuf/grpc,geffzhang/grpc,Crevil/grpc,ctiller/grpc,ananthonline/grpc,stanley-cheung/grpc,leifurhauks/grpc,deepaklukose/grpc,jboeuf/grpc,ppietrasa/grpc,msmania/grpc,y-zeng/grpc,pszemus/grpc,jcanizales/grpc,firebase/grpc,mehrdada/grpc,7anner/grpc,thunderboltsid/grpc,soltanmm-google/grpc,dgquintas/grpc,baylabs/grpc,kriswuollett/grpc,simonkuang/grpc,pszemus/grpc,yugui/grpc,philcleveland/grpc,apolcyn/grpc,ppietrasa/grpc,LuminateWireless/grpc,stanley-cheung/grpc,kskalski/grpc,apolcyn/grpc,baylabs/grpc,kumaralokgithub/grpc,andrewpollock/grpc,jboeuf/grpc,nicolasnoble/grpc,thunderboltsid/grpc,rjshade/grpc,murgatroid99/grpc,infinit/grpc,perumaalgoog/grpc,ejona86/grpc,mehrdada/grpc,MakMukhi/grpc,kriswuollett/grpc,kpayson64/grpc,makdharma/grpc,makdharma/grpc,yang-g/grpc,a11r/grpc,simonkuang/grpc,firebase/grpc,grpc/grpc,nicolasnoble/grpc,philcleveland/grpc,PeterFaiman/ruby-grpc-minimal,thinkerou/grpc,PeterFaiman/ruby-grpc-minimal,carl-mastrangelo/grpc,jboeuf/grpc,nicolasnoble/grpc,fuchsia-mirror/third_party-grpc,donnadionne/grpc,msiedlarek/grpc,msiedlarek/grpc,y-zeng/grpc,tamihiro/grpc,ipylypiv/grpc,firebase/grpc,yang-g/grpc,jtattermusch/grpc,stanley-cheung/grpc,daniel-j-born/grpc,royalharsh/grpc,mehrdada/grpc,perumaalgoog/grpc,msiedlarek/grpc,jcanizales/grpc,donnadionne/grpc,ananthonline/grpc,y-zeng/grpc,LuminateWireless/grpc,nicolasnoble/grpc,matt-kwong/grpc,sreecha/grpc,tengyifei/grpc,murgatroid99/grpc,murgatroid99/grpc,vsco/grpc