V8/Node.js increase max allowed String length

Question

AFAIK V8 has a known hard limit on the length of allowed Strings. Trying to parse >500MB Strings will pop the error:

Invalid String Length

Using V8 flags to increase the heap size doesn't make any difference

$ node --max_old_space_size=5000 process-large-string.js

I know that I should be using Streams instead. However is there any way to increase the maximum allowed String length anyway?

Update: Answer from @PaulIrish below indicates they upped it to 1GB - but it's still not user-configurable

Paul Irish · Accepted Answer · 2017-12-19 00:58:24Z

16

In summer 2017, V8 increased the maximum size of strings from ~256MB to ~1GB. Specifically, from 2^28 - 16 to 2^30 - 25 on 64-bit platforms. V8 ticket.

This change landed in:

V8: 6.2.100
Chromium: 62.0.3167.0
Node.js: 9.0.0

edited Dec 19, 2017 at 0:58

answered Dec 12, 2017 at 20:48

Paul Irish

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Daniel Sokolowski Over a year ago

This appears to have regressed back tp 2^28 due to pointer compression and recently bumped back up to 2^29 (0.5GB) as per github.com/v8/v8/commit/… :(

jmrk · Accepted Answer · 2017-06-14 09:09:07Z

14

Sorry, no, there is no way to increase the maximum allowed String length.

It is hard-coded in the source, and a lot of code implicitly relies on it, so while allowing larger strings is known to be on people's wishlist, it is going to be a lot of work and won't happen in the near future.

answered Jun 14, 2017 at 9:09

jmrk

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4 Comments

nicholaswmin Over a year ago

Do you happen to know the reason for this limitation? Why does String have that particular max length in V8?

jmrk Over a year ago

It dates back all the way to 2010. Back then, 512MB was the overall heap limit, and I guess it was a no-brainer to decide that no single string could/should be bigger than the heap ;-) (512 MB = memory consumption of a UTF-16 string with length 2^28.)

Paul Irish Over a year ago

This is no longer the case. See my answer.

guido Over a year ago

@PaulIrish well , it actually still IS the case that there is a maximum limit; the limit was increased to roughly 1gig

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