Nesting node async.eachSeries
Been fighting with async module for half a day but can't get it to work properly when nesting few levels. A bit of a lengthy post due to code, but please bare with me, all code should run ok.
So this works ok:
var async = require('async') var myarr = ["Outer - A", "Outer - B"]; var myarr2 = ["Inner - A", "Inner - B"]; var innerComplete = true; async.eachSeries(myarr, function( item, outerCallback) { console.log('Processing item ' + item); async.series([ function(callback) { takeTime(2000, item, callback) }, function(callback) { takeTime(1000, item, callback) }, function(callback) { outerCallback(); } ], function(err) { console.log("---OUTER SEQUENCE---") }) }, function(err){ console.log("---OUTER LOOP---") }); function takeTime(ms, msg, callback) { console.log("Starting " + ms + " ms task from " + msg); setTimeout( function() { console.log("Finished " + ms + " ms task from " + msg); callback(); }, ms); }
And it outputs everything nicely in sequence like this:
Processing item Outer - A Starting 2000 ms task from Outer - A Finished 2000 ms task from Outer - A Starting 1000 ms task from Outer - A Finished 1000 ms task from Outer - A Processing item Outer - B Starting 2000 ms task from Outer - B Finished 2000 ms task from Outer - B Starting 1000 ms task from Outer - B Finished 1000 ms task from Outer - B ---OUTER LOOP---
But when I try to nest another eachSeries loop into it like this:
var async = require('async') var myarr = ["Outer - A", "Outer - B"]; var myarr2 = ["Inner - A", "Inner - B"]; var innerComplete = true; async.eachSeries(myarr, function( item, outerCallback) { console.log('Processing item ' + item); async.series([ function(callback) { takeTime(2000, item, callback) }, function(callback) { takeTime(1000, item, callback) }, function(callback) { async.eachSeries(myarr2, function( item2, outerCallback2) { console.log('Processing item ' + item2); async.series([ function(callback2) { takeTime(2000, item2, callback2) }, function(callback2) { takeTime(1000, item2, callback2) } ], function(err) { console.log('---INNER SEQUENCE---') }) }, function(err){ console.log("---INNER LOOP---") }); outerCallback(); } ], function(err) { console.log("---OUTER SEQUENCE---") }) }, function(err){ console.log("---OUTER LOOP---") }); function takeTime(ms, msg, callback) { console.log("Starting " + ms + " ms task from " + msg); setTimeout( function() { console.log("Finished " + ms + " ms task from " + msg); callback(); }, ms); }
It loses the execution order when entering the second eachSeries loop like this:
Processing item Outer - A Starting 2000 ms task from Outer - A Finished 2000 ms task from Outer - A Starting 1000 ms task from Outer - A Finished 1000 ms task from Outer - A Processing item Inner - A Starting 2000 ms task from Inner - A Processing item Outer - B Starting 2000 ms task from Outer - B Finished 2000 ms task from Inner - A Starting 1000 ms task from Inner - A Finished 2000 ms task from Outer - B Starting 1000 ms task from Outer - B Finished 1000 ms task from Inner - A ---INNER SEQUENCE--- Finished 1000 ms task from Outer - B Processing item Inner - A Starting 2000 ms task from Inner - A ---OUTER LOOP--- Finished 2000 ms task from Inner - A Starting 1000 ms task from Inner - A Finished 1000 ms task from Inner - A ---INNER SEQUENCE---
I also tried out waterfall, mapSeries etc, but with same or otherwise messed up sequence of execution. Am I doing something wrong or doesn't the async module support such nesting?
You're not calling the outerCallback2
, you're not calling the callback
, and you're calling the outerCallback
immediately.
Fixed:
async.eachSeries(myarr, function( item, outerCallback) {
,----------------------------------------'
| console.log('Processing item ' + item);
| async.series([
| function(callback) {
| `--------------,
| takeTime(2000, item, callback)
| },
| function(callback) {
| `--------------,
| takeTime(1000, item, callback)
| },
| function(callback) {
| ,-----------'
| | async.eachSeries(myarr2, function( item2, outerCallback2) {
| | ,---------------------------------------------'
| | | console.log('Processing item ' + item2);
| | | async.series([
| | | function(callback2) {
| | | takeTime(2000, item2, callback2)
| | | },
| | | function(callback2) {
| | | takeTime(1000, item2, callback2)
| | | }
| | | ], function(err) {
| | | console.log('---INNER SEQUENCE---')
| | `---> outerCallback2(err); // <<<
| | })
| | }, function(err){
| | console.log("---INNER LOOP---");
| `---> callback(err); // <<<
| });
| }
| ], function(err) {
| console.log("---OUTER SEQUENCE---")
`---> outerCallback(err); // <<<
})
}, function(err){
console.log("---OUTER LOOP---")
console.log("everything done");
});
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