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More useful error than toString failed when Buffer length greater than kMaxLength? #3175
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256 MB is the limit for strings in V8 so no, it's not a regression. What would you report in more detail?
Anything would be better than that TBH.
Reacted by Pat Myron, Petr Vnenk, Christopher Liedelt and Zakery ClarkeIt's not obvious to the user what's actually gone wrong.
How about "Cannot create string larger than 256MB"? Seems a lot clearer to me.
Reacted by Chris, Tanner Faulkner, Sam Stefan, William Dias, Luca Steeb, Lloyd Brookes, Jose, Douglas Duhaime, Daniel Bankhead, garrypas and 54 moreI think a pull request to that effect would be acceptable.
But is that the only error that can occur? Looking at the code at the moment, the check is pretty basic – is there no way of getting more detail as to why
resultmay beundefined?Not at the moment, no. The undefined value trickles down from StringBytes::Encode() in src/string_bytes.h. I don't think there are other code paths that return an empty
Local<String>but I didn't check exhaustively.FWIW, v8 (I assume?) spits out a slightly better error when trying to concat strings:
$ node -p 'var a = "a"; for (var i = 0; i < 27; i++) a = a + a; a.length' 134217728 $ node -p 'var a = "a"; for (var i = 0; i < 28; i++) a = a + a; a.length' [eval]:1 var a = "a"; for (var i = 0; i < 28; i++) a = a + a; a.length ^ RangeError: Invalid string length at [eval]:1:49 at Object.exports.runInThisContext (vm.js:54:17) at Object.<anonymous> ([eval]-wrapper:6:22) at Module._compile (module.js:434:26) at node.js:566:27 at doNTCallback0 (node.js:407:9) at process._tickCallback (node.js:336:13)
Is the size limit exposed at all? If it were I'd be happy to add a PR that checks, in the case of an
undefinedresult, whether the Buffer length is greater than it.I don't think it is exposed in JS. The exact limit is
(1 << 28) - 16(268435440) and is defined inLine 2083 in 64beab0
- changed the title
[-]More useful error than `toString failed`?[/-][+]More useful error than `toString failed` when Buffer length greater than kMaxLength?[/+]on Oct 4, 2015 I would love to take a stab at this if people are open to it.
/cc @jasnell
Reacted by Jose and Kyle KelleyReacted by Jose and Kyle KelleyWorks for me!
On Oct 6, 2015 12:49 PM, "Myles Borins" notifications@github.com wrote:I would love to take a stab at this if people are open to it.
/cc @jasnell https://github.com/jasnell
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#3175 (comment).@MylesBorins Seems the discussion addresses more than just the error message. Mind identifying the specifics of what you'll be working on?
I specifically was interested in a better error message when toString is called on a Buffer larger than kStringMaxLength
That seemed like a pretty easy one to knock out (I've basically got it done already).
@MylesBorins I think the discussion was around how to detect the limit though – have you exposed
kMaxLength?27 remaining items
For what it's worth, the error message here has been marginally improved to
Error: "toString()" failed(although I'm not sure why the quotation marks are used--that seems peculiar--but the addition of parentheses are a marginal improvement).And, of course, it still doesn't indicate why it failed though.
Reacted by Bill Morris, Aaron Cordova and Maxim Vorobjov- added a commit that references this issue
on May 6, 2017 I... don't understand why the limit is 256 MB :(
Reacted by Kyle Kelley and Paul DraperThere's an issue open on v8 too, if you'd like to star it: https://bugs.chromium.org/p/v8/issues/detail?id=6148
Can we rename the issue from "String length limit is small-ish" to "String length limit is small-af"
Reacted by Kyle Kelley, Basit Mustafa, fengthedroid, Jesse Vander Does and Sarat AddepalliReacted by Basit Mustafa, fengthedroid, devildelta, Shalom Yerushalmy and eglyecyriacoGreat news! v8 has upped the limit to ~1GB on 64-bit archs: https://chromium-review.googlesource.com/c/570047
Hopefully it comes with a nicer error message when it fails too (although that's possibly still a Node.js responsibility?)
Reacted by Luciano Mammino and si- added a commit that references this issue
on Apr 7, 2018 After 63eb267 this now returns a message
Cannot create a string larger than 0x3fffffe7 byteswith the error code set toERR_STRING_TOO_LARGE.Reacted by Ouyang YadongI am running into this issue when I try to download .tar file via request and piping it to tar.x(). Does this issue imply that the maximum body size that I can download via request.get() is 1G for 64-bit machine?
nvm.. I just had to set "encoding: null" ... which prevents the body to be passed to toString()
- added a commit that references this issue
on Jul 27, 2026
I'm assuming there's some sort of memory constraint trying to convert buffers into strings?
But:
Firstly, I'm not sure that this should even be an error (are we really only limited to 256MB? That's... not very much). This seems to have been addressed in the past, but I feel like a regression might have occurred: #1374 (comment)
But that aside, can we actually detect what the error is and report on it in a more detailed way? The current
toStringcheck provides little insight.