[zeromq-dev] Maximum message size on Windows

[Merijn Verstraaten]

Well, considering the wire protocol is limited to long sizes of 64bit unsigned, I guess it would be appropriate to consider 2^64 - 1 bytes the maximum message size. Which is almost the same as "no limit" given current hardware circumstances, I guess.

Cheers,
Merijn

On Aug 21, 2013, at 12:05 , Alan Ward wrote:
> Hi Pieter,
> Thanks for the quick response.
> 
> Alan
> 
> -----Original Message-----
> From: zeromq-dev-bounces at lists.zeromq.org
> [mailto:zeromq-dev-bounces at lists.zeromq.org] On Behalf Of Pieter Hintjens
> Sent: 21 August 2013 11:52
> To: ZeroMQ development list
> Subject: Re: [zeromq-dev] Maximum message size on Windows
> 
> There is no maximum defined message size. What you are seeing is the default
> stack size of 1MB being hit by your use of a huge local variable.
> 
> In general do not put anything larger than a few kilobytes into local
> storage since depending on the build, the stack can be as small as 4KB. You
> don't get any warning, just a nasty crash.
> 
> Use dynamic allocation, and it will work up to the limit of heap memory.
> 
> -Pieter
> 
> On Wed, Aug 21, 2013 at 12:43 PM, Alan Ward <alan.ward at btinternet.com>
> wrote:
>> Hi,
>> I have an application that I have been developing on Linux (Ubuntu) 
>> for a few months.
>> I am now trying to port it to Windows.
>> 
>> After battling with Visual Studio for a while I now have the code 
>> executing, but have immediately hit a problem with the maximum message
> size.
>> 
>> On Linux I have a maximum message size of 1Mb (1048576). This is 
>> fairly arbitrary so I can reduce it.
>> On Windows this causes zmq_recv to crash. I have found that the 
>> threshold is around 1027830.
>> 
>> I am using the 32-bit version of zeromq (3.2.3) on Windows and 64-bit
>> (3.2.2) on Linux.
>> 
>> The following code snippet causes an exception on my system.
>> 
>> #include <zmq.h>
>> #include <stdio.h>
>> #include <tchar.h>
>> #include <string.h>
>> #include <assert.h>
>> 
>> int _tmain(int argc, _TCHAR* argv[])
>> {
>>    int rc;
>>    char buffer [ 1027830 ];
>>    void *context;
>>    void *responder;
>>    size_t msg_size;
>> 
>>    puts("start");
>>    context = zmq_ctx_new ();
>>    responder = zmq_socket (context, ZMQ_REP);
>>    rc = zmq_bind (responder, "tcp://*:5555");
>>    if ( rc != 0 ) { printf("zmq_bind error: rc:%d:errno:%d\n", rc, 
>> errno); return 1; }
>> 
>>    msg_size = zmq_recv (responder, buffer, 2048, 0);
>> 
>>    return 0;
>> }
>> 
>> Is there a defined maximum size? I did search for some information on 
>> this a while ago, but found nothing.
>> 
>> Regards,
>> Alan
>> 
>> _______________________________________________
>> zeromq-dev mailing list
>> zeromq-dev at lists.zeromq.org
>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
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