node.js - How to deal with readFile when file is currently written to -

this might bit fuzzy have node app writes small counter file after doing bunch of stuff:

fs.readfile( blender.log , function(error, data) { //read log file     if( error ) {         throw error;     }      counter = parseint( data ) + 1; //add blend      if(!isnan( counter )) { //check if number number         fs.writefile( blender.log, counter, function(error) {             if( error ) {                 throw error;             }              blender.debugging( 'counter: added', 'report' );         });     }     else { //throw error         blender.log.error('             counter number not valid ("' + counter + '"). leaving alone now!');     } }); 

due high demand on app more not isnan in callback of readfile because file open write writefile previous instance.

(it interesting me there no errors thrown though)

how deal this? don't want make blocking write keep app fast perhaps queue write? open though. :)

thanks

it looks want implemention file counter, makesure it'is atomic, need this:

lock file read counter file increment counter write counter file unlock file 

suggest use fs-ext module, if want lock file.

another way: use redis store counter, have atomic increment, , it's performance better because without need write disk frequently.