Is there a limit on the size of a string in JSON with Node.js?

Question

A section of my Node.js application involves receiving a string as input from the user and storing it in a JSON file. JSON itself obviously has no limit on this, but is ther

Answer 1

The maximum string size in "vanilla" nodeJS (v0.10.28) is in the ballpark of 1GB.

If your are in a hurry, you can test the maximum supported string size with a self doubling string. The system tested has 8GB of RAM, mostly unused.

x = 'x';
while (1){ 
     x = ''+x+x; // string context
     console.log(x.length);
}

2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16384
32768
65536
131072
262144
524288
1048576
2097152
4194304
8388608
16777216
33554432
67108864
134217728
268435456
536870912
FATAL ERROR: JS Allocation failed - process out of memory
Aborted (core dumped)

In another test I got to 1,000,000,000 with a one char at a time for loop.

Now a critic might say, "wait, what about JSON. the question is about JSON!" and I would shout THERE ARE NO JSON OBJECTS IN JAVASCRIPT the JS types are Object, Array, String, Number, etc.... and as JSON is a String representation this question boils down to what is the longest allowed string. But just to double check, let's add a JSON.stringify call to address the JSON conversion.

Code

x = 'x';
while (1){ 
     x = ''+x+x; // string context
     console.log(JSON.stringify({a:x}).length);
}

Expectations: the size of the JSON string will start greater than 2, because the first object is going to stringify to '{"a":"xx"}' for 10 chars. It won't start to double until the x string in property a gets bigger. It will probably fail around 256M since it probably makes a second copy in stringification. Recall a stringification is independent of the original object.

Result:

10
12
16
24
40
72
136
264
520
1032
2056
4104
8200
16392
32776
65544
131080
262152
524296
1048584
2097160
4194312
8388616
16777224
33554440
67108872
134217736
268435464

Pretty much as expected....

Now these limits are probably related to the C/C++ code that implements JS in the nodeJS project, which at this time I believe is the same V8 code used in Chrome browsers.

There is evidence from blog posts of people recompiling nodeJS to get around memory limits in older versions. There are also a number of nodejs command line switches. I have not tested the effect of any of this.