refactor topic subscribers' notification in order to optimize it
refactor topic subscribers' notification in order to optimize it

ttyS15/pybbm,wengole/pybbm,jonsimington/pybbm,hovel/pybbm,just-work/pybbm,skolsuper/pybbm,jonsimington/pybbm,hovel/pybbm,hovel/pybbm,artfinder/pybbm,wengole/pybbm,NEERAJIITKGP/pybbm,just-work/pybbm,webu/pybbm,springmerchant/pybbm,onecue/pybbm,DylannCordel/pybbm,artfinder/pybbm,wengole/pybbm,jonsimington/pybbm,onecue/pybbm,webu/pybbm,springmerchant/pybbm,springmerchant/pybbm,NEERAJIITKGP/pybbm,artfinder/pybbm,katsko/pybbm,DylannCordel/pybbm,just-work/pybbm,katsko/pybbm,ttyS15/pybbm,skolsuper/pybbm,NEERAJIITKGP/pybbm,onecue/pybbm,katsko/pybbm,ttyS15/pybbm,DylannCordel/pybbm,skolsuper/pybbm,webu/pybbm