Long chain promise => Out of memory

Bluebird 3.3.4 and node v5.10.1.

I’m not sure if this is a bug or an expected behaviour that the earlier resolved promised in a chain doesn’t get collected up in GC. This might even be a node problem.

var Promise = require('bluebird')

function add(x){
  return x+1
}

var a = Promise.resolve(0)
for(var i=0;i<10e8;i++){
  a = a.then(add)
}

node screams with message like this

<--- Last few GCs --->

    7440 ms: Scavenge 1413.8 (1458.1) -> 1413.8 (1458.1) MB, 24.1 / 0 ms (+ 0.9 ms in 1 steps since last GC) [allocation failure] [incremental marking delaying mark-sweep].
    8138 ms: Mark-sweep 1413.8 (1458.1) -> 1413.8 (1458.1) MB, 698.2 / 0 ms (+ 0.9 ms in 1 steps since start of marking, biggest step 0.9 ms) [last resort gc].
    8829 ms: Mark-sweep 1413.8 (1458.1) -> 1413.8 (1458.1) MB, 691.4 / 0 ms [last resort gc].


<--- JS stacktrace --->

==== JS stack trace =========================================

Security context: 0x3d33367e3ac1 <JS Object>
    1: _then [xxx/node_modules/bluebird/js/release/promise.js:~217] [pc=0x1df6cf8b05d6] (this=0x35cfdd004101 <a Promise with map 0x1c4d6bb33c21>,didFulfill=0x2597f0bb95a9 <JS Function add (SharedFunctionInfo 0x2597f0b4ae79)>,didReject=0x3d3336704189 <undefined>,_=0x3d3336704189 <undefined>,receiver=0x3d3336704189 <undefined>,internalData=0x3d...

FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - process out of memory
Abort trap: 6

I know I could use each and such. But, the specific problem I’m trying to solve will involve stream of random data which I do not want to store the entire thing in a memory which will need to put in to db.

Is there a way to get around this?

[petkaantonov]

No nextTick doesn’t mean the callbacks are called, only the callback being called means the callback has been called. setImmediate scheduler is used in node so the same code probably works with a setTimeout rather than nextTick which won’t allow setImmediate to trigger.

[piti118]

For unsuspecting passerby in the future, this one works (very slowly), but it works. (One could group it so setImmediate doesn’t get called so often)

var Promise = require('bluebird')

function add(x){
  return x+1
}

var a = Promise.resolve(0)
function f(i){
  if(i>0){
    a=a.then(add)
    setImmediate(()=>f(i-1))
    if(i%100000==0){console.log(i)}
  }else{
    a.then(console.log)
  }
}

f(10e7)