--- name: "MPI_Lookup_name" section: "3" platform: "linux" package: "openmpi" version: "5.0.11-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/MPI_Lookup_name" --- # MPI\_Lookup\_name(3) ``` MPI_Lookup_name - Finds port associated with a service name ``` ## SYNTAX ### C Syntax ``` #include int MPI_Lookup_name(const char *service_name, MPI_Info info, char *port_name) ``` ### Fortran Syntax ``` USE MPI ! or the older form: INCLUDE 'mpif.h' MPI_LOOKUP_NAME(SERVICE_NAME, INFO, PORT_NAME, IERROR) CHARACTER*(*) SERVICE_NAME, PORT_NAME INTEGER INFO, IERROR ``` ### Fortran 2008 Syntax ``` USE mpi_f08 MPI_Lookup_name(service_name, info, port_name, ierror) CHARACTER(LEN=*), INTENT(IN) :: service_name TYPE(MPI_Info), INTENT(IN) :: info CHARACTER(LEN=MPI_MAX_PORT_NAME), INTENT(OUT) :: port_name INTEGER, OPTIONAL, INTENT(OUT) :: ierror ``` ## INPUT PARAMETERS - • **service\_name**: A service name (string). - • **info**: Options to the name service functions (handle). ## OUTPUT PARAMETERS - • **port\_name**: a port name (string). - • **ierror**: Fortran only: Error status (integer). ## DESCRIPTION This function retrieves a *port\_name* published under *service\_name* by a previous invocation of *MPI\_Publish\_name*. The application must supply a *port\_name* buffer large enough to hold the largest possible port name (i.e., MPI\_MAX\_PORT\_NAME bytes). ## INFO ARGUMENTS The following keys for *info* are recognized: ``` Key Type Description --- ---- ----------- range char * Scope in which to search for the service name. See the NAME SCOPE section below. ``` The *range* info key accepts one of two string values: - ***nspace*: Restrict the operation to processes in the same MPI job (PMIx** namespace) as the calling process. *session*: Apply the operation across all processes in the same session. If the *info* argument is **MPI\_INFO\_NULL**, or is a valid info object that does not contain a *range* key, *session* scope is used. Because *MPI\_Publish\_name*, *MPI\_Lookup\_name*, and *MPI\_Unpublish\_name* all share this default, a name published with **MPI\_INFO\_NULL** is found by a lookup with **MPI\_INFO\_NULL**. Any other value for *range* results in an error. ## NAME SCOPE Open MPI supports two name scopes, selected by the *range* info key: *nspace* and *session*. *nspace* scope restricts the (service\_name, port\_name) pair to processes in the publisher’s own MPI job, i.e., processes sharing the publisher’s PMIx namespace. *session* scope makes the pair visible to every process in the same PMIx session. This includes jobs started by separate **mpirun** invocations that share a persistent DVM or scheduler allocation, as well as jobs created via *MPI\_Comm\_spawn*. *session* is the default scope. The same scope must be used to publish, look up, and unpublish a given service name. *MPI\_Unpublish\_name* returns an error if the service name is not found in the indicated scope. For a more detailed description of scoping rules, please see the *MPI\_Publish\_name* man page. ## ERRORS Almost all MPI routines return an error value; C routines as the return result of the function and Fortran routines in the last argument. Before the error value is returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) is called. If no communication object is associated with the MPI call, then the call is considered attached to MPI\_COMM\_SELF and will call the associated MPI error handler. When MPI\_COMM\_SELF is not initialized (i.e., before *MPI\_Init*/*MPI\_Init\_thread*, after *MPI\_Finalize*, or when using the Sessions Model exclusively) the error raises the initial error handler. The initial error handler can be changed by calling *MPI\_Comm\_set\_errhandler* on MPI\_COMM\_SELF when using the World model, or the mpi\_initial\_errhandler CLI argument to mpiexec or info key to *MPI\_Comm\_spawn*/*MPI\_Comm\_spawn\_multiple*. If no other appropriate error handler has been set, then the MPI\_ERRORS\_RETURN error handler is called for MPI I/O functions and the MPI\_ERRORS\_ABORT error handler is called for all other MPI functions. Open MPI includes three predefined error handlers that can be used: - • **MPI\_ERRORS\_ARE\_FATAL** Causes the program to abort all connected MPI processes. - • **MPI\_ERRORS\_ABORT** An error handler that can be invoked on a communicator, window, file, or session. When called on a communicator, it acts as if *MPI\_Abort* was called on that communicator. If called on a window or file, acts as if *MPI\_Abort* was called on a communicator containing the group of processes in the corresponding window or file. If called on a session, aborts only the local process. - • **MPI\_ERRORS\_RETURN** Returns an error code to the application. MPI applications can also implement their own error handlers by calling: - • *MPI\_Comm\_create\_errhandler* then *MPI\_Comm\_set\_errhandler* - • *MPI\_File\_create\_errhandler* then *MPI\_File\_set\_errhandler* - • *MPI\_Session\_create\_errhandler* then *MPI\_Session\_set\_errhandler* or at *MPI\_Session\_init* - • *MPI\_Win\_create\_errhandler* then *MPI\_Win\_set\_errhandler* Note that MPI does not guarantee that an MPI program can continue past an error. See the *MPI man page* for a full list of *MPI error codes*. See the Error Handling section of the MPI-3.1 standard for more information. **SEE ALSO:** - • *MPI\_Publish\_name* - • *MPI\_Open\_port* ## COPYRIGHT 2003-2026, The Open MPI Community