Sending failed when the amount of sequence type data is large

[zip-link]

Using the default QoS configuration of version 2.5.0, when transmitting sequence data, when the number of elements of sequence is relatively large, it will fail to send after matching the subscriber. After releasing printing, serialization failed. How to solve this problem?

There are warnings below：
2022-03-10 10:23:54.115 [RTPS_WRITER Info] 0.0.3.c2 Sending Heartbeat (1 - 1) -> Function send_heartbeat_nts_
2022-03-10 10:23:54.929 [RTPS_WRITER Warning] RTPSWriter:Serialization returns false -> Function perform_create_new_change
2022-03-10 10:23:56.917 [RTPS_WRITER Info] Sending relevant changes as DATA/DATA_FRAG messages -> Function add_data
2022-03-10 10:23:56.917 [RTPS_WRITER Info] Sending INFO_TS message -> Function add_info_ts_in_buffer

[EduPonz]

Hi @zip-link ,

We would need more information to reproduce your issue:

• Which OS are you using?
• How are you compiling Fast DDS (CMake flags, etc.)?
• What is a relative large number of elements for a sequence?

Ideally, some short of reproducer would be nice; we normally ask for a Dockerfile, as that way the reproducer is self contained.

Thanks!

[LakeFusion]

I've also have this issue. It seems if there is no maximum size definition for a sequence, fastddsgen simply takes 100 as the limit.

To override the limit of 100 elements, you can define a constant and use it as maximum size for the sequence like this:

const int32 MAX_SIZE = 2097152;
...
sequence<uint8, MAX_SIZE> data;

[zip-link]

Hi,@EduPonz
I tried to use the latest fastddsgen version 2.1.1 to generate serialization code, but this problem still exists. I think there is still a problem of boundary recognition in the code, but I won't understand it for a while

[zip-link]

@LakeFusion thank you,
I've tried your method. It's really useful. You can specify the size when you don't know the IDL definition before. Is this the standard IDL definition method?

[LakeFusion]

No problem @zip-link . I don't think it is the standard way but it is a valid IDL syntax which worked for my case. Somehow ROS2 IDLs just work without such limits.

[MiguelCompany]

@LakeFusion @zip-link That is standard IDL syntax. On IDL 4.2, the grammar for sequence is defined as

<sequence_type> ::= "sequence" "<" <type_spec> "," <positive_int_const> ">"
                |   "sequence" "<" <type_spec> ">"