Introduction
This is a documentation of RTI Connext Micro resource limits that are not configurable in a QoS policy or property. Note that not every single constant used in RTI Connext Micro is addressed. The focus is on resource limits that may prevent an application using RTI Connext Micro from behaving correctly. For example, the maximum number of participants that can be discovered on a node may impact an application. On the other hand, a resource limit that has no functional impact, for example the maximum length of the discovery plugin name, is not described in this document.
When a resource limit is exceeded an error message is logged. An explanation can be found in the documentation. Note that some resource limits may be exceeded when calling an API and others may be exceeded as part of processing incoming data. Thus, it may be necessary to look at log output to see the failure reason.
Although RTI Connext Micro can be compiled from source it is recommended to consult with RTI before making any changes to the hard coded limits.
Summary
Resource | Limit |
Number of domain participants per OS process | 8 |
Max topic name length | 255 |
Max type name length | 255 |
Max number of destination addresses for a data-writer | 4 |
Max number of destination addresses for a data-reader | 4 |
Max number of user registered plugins | 2 |
Max number of readers and writers in a domain participant | 60 |
Max number of discovery plugins used by a domain participant | 1 |
Max number of participants that can be reached per unicast address | 6 |
Max number of transports used by RTPS | 4 |
Max number of announced receive addresses for discovery data by a domain participant | 4 |
Max number of announced receive addresses for user-data data by a domain participant | 4 |
Max number of addresses that can be received (per meta-unicast, meta-multicast, user-unicast, user-multicast) | 4 |
Operating Services API (OSAPI)
- Maximum number of object ids: 2^32-1
- DDS objects require a unique object_id. The encoding dictated by the RTPS specification limits the number of DDS objects within a domain participant to 2^24.
- User impact: None.
- Maximum number of timers: 8
- Each domain participant allocates 1 timer.
- User impact: The maximum number of domain participants in a single OS process is limited to 8. This limit is based on empirical data; only specialized applications such as tools typically use more than 2 domain participants.
DDS C API
- Maximum Topic name length: 255 (including NUL termination)
- The limit is specified as 256 including NUL termination in the RTPS specification, refer to 9.6.2.2.2 in the RTPS specification (OMG formal/2009-01-05).
- Maximum Type name length: 255 (including NUL termination)
- The limit is specified as 256 including NUL termination in the RTPS specification, refer to 9.6.2.2.2 in the RTPS specification (OMG formal/2009-01-05).
- Maximum number of DDS routes from data-reader to data-writer: 2
- This limit constrains the number of paths to a matched data-writer.
- User impact: None. Currently an end-point can only be reached via RTPS and intra-participant interface.
- Maximum number of RTPS routes per remote writer: 4
- This limit determines the maximum number of RTPS routes a data-reader can have per matched data-writer.
- User impact: A data-writer can have at most 4 destination addresses.
- Maximum number of RTPS transports per remote writer: 4
- This limits determines the maximum numbers of RTPS transports a data-reader can have per matched data-writer.
- User impact: RTPS can send to at most 4 local transports. Currently RTI Connext Micro only ships with 1 transport, thus at most 3 user transports can be registered together with the RTI Connext Micro UDP transport.
- Maximum number of matched data-writers (per data-reader): 100,000,000
- This limit determines how many data-writers each data-reader can match.
- Maximum number of matched data-readers (per data-writer): 100,000,000
- This limit determines how many data-readers each data-writer can match.
- Maximum number of DDS routes from data-writer to data-reader: 4
- This limit constrains the number of locators a data-reader can be reached via. For example a maximum of 4 unicast addresses.
- User impact: None. Currently an end-point can only be reached via RTPS and intra-participant interface.
- Maximum number of RTPS paths per remote reader: 4
- This limits determines the maximum numbers of RTPS routes a data-writer can have per matched data-reader.
- User impact: A data-writer can have at most 4 destination addresses.
- Maximum number of RTPS transports per remote writer: 4
- This limits determines the maximum numbers of RTPS transports a data-reader can have per matched data-writer.
- User impact: RTPS can send to at most 4 local transports. Currently RTI Connext Micro only ships with 1 transport, thus at most 3 user transports can be registered in addition to the RTI Connext Micro UDP transport.
- Maximum number of discovery-/transport-/history-plugins which can be registered: 10
- User impact: Currently 8 out of the 10 is used by RTI.
- Maximum number of tables which be created in the participant table: 200
- This limit limits how many unique entities and tables can be created.
- User impact: The number of readers and writers per participant is limited to 60.
- Maximum number of locators of each type which can be sent in the participant announcement: 4
- This limit determines the number of unique network address that can be advertised as part of discovery. The limit is per locator type. That is, the limit is applicable to discovery and user-data (total of 4 each)
- Maximum number of discovery plugins which can be used by the domain participant: 1
- User impact: Must choose either static or dynamic discovery.
Dynamic Discovery Plugin (DPDE)
- Maximum number of received locators: 4
- This limit determines the number of unique network address that can be advertised as part of discovery.
- The limit is per locator type. That is, the same limit is applicable to discovery unicast, discovery multicast, user-data unicast, and user-data multicast.
- Maximum number of domain participant which can be reached per unicast peer address: 6
- Discovery of remote participants are limited to participant id 0-5.
- User impact: RTI Connext Micro can only discover up to 6 domain participants on each node discovered via unicast.
Static Discovery Plugin (DPSE)
- Maximum number of received locators: 4
- This limit determines the number of unique network address that can be advertised as part of discovery.
- The limit is per locator type. That is, the same limit is applicable to discovery unicast, discovery multicast, user-data unicast, and user-data multicast.
- Maximum number of domain participant which can be reached per unicast peer address: 6
- Discovery of remote participants are limited to participant id 0-5.
- User impact: RTI Connext Micro can only discover up to 6 domain participants on each node discovered via unicast.
RTPS Protocol Implementation (RTPS)
- Unlimited max_samples is defined as 100000000
- Maximum number of external RTPS interfaces: 16
- This limits the number of participants to 16 per OS process.
- This limit is reduced to 8 due to the OS limit.