ZeroMQ Message Size Length Limit?

Question

Suppose that several machines are interacting together using python's zeroMQ client.

These messages are naturally formatted as strings.

Is there a limit to the length of a message (string)?

I added my 2 cents below. Let me know your thoughts. – meawoppl Jan 26 '16 at 05:26 — meawoppl, Jan 26 '16 at 05:26

score 21 · Accepted Answer · answered Jul 01 '11 at 06:53

21

There is no limit to the size of messages being sent however small messages are handled differently than large messages (see here).

The max size of a small messages is defined in the source code at 30 bytes (see here, look for ZMQ_MAX_VSM_SIZE).

answered Jul 01 '11 at 06:53

kwo

2

Clearly you never have tried to send something larger than 2^31 :) – meawoppl Jan 26 '16 at 05:26
1

ZMQ_MAXMSGSIZE is an int64, so 2ˆ63 is more likely the limit – Mathieu Longtin Apr 18 '16 at 13:48
They increased the size limit. :) It is now 33 bytes for 64bit and 37 bytes for 32bit platforms. https://github.com/zeromq/libzmq/blob/master/src/msg.hpp#L137 – Björn Lindqvist Nov 20 '16 at 01:08

score 5 · Answer 2 · answered Jul 27 '15 at 16:26

5

There is the socket option ZMQ_MAXMSGSIZE which causes a peer sending an oversized message to be disconnected, but the default is "no limit".

answered Jul 27 '15 at 16:26

Rob Agar

1

Does not answer the question. – meawoppl Jan 26 '16 at 06:56
@meawoppl `but the default is "no limit"` does answer the question! IMHO this here is currently the most helpful answer (if you do not look in the comments of the accepted answer). – Tino Jun 08 '21 at 00:37

score 2 · Answer 3 · answered Jul 09 '13 at 22:06

2

No limit

As for small size messages transmitted within zmq_msg_t structures, their limit is 29 bytes (for zmq version 3.2.2)

answered Jul 09 '13 at 22:06

cloudcell

score 2 · Answer 4 · answered Jan 26 '16 at 05:25

2

Some socket types support up to 2^64, but some less than 2^31.

You should build a protocol that keeps chunks below that size anyway, but this is the real answer.

answered Jan 26 '16 at 05:25

meawoppl

4 Answers4