Collecting Tracing Data From a Running Program

If you want to collect any kind of tracing data, you must preload the Collector library, libcollector.so, before you run your program, because the library provides wrappers to the real functions that enable data collection to take place. In addition, the Collector adds wrapper functions to other system library calls to guarantee the integrity of performance data. If you do not preload the Collector library, these wrapper functions cannot be inserted. See Using System Libraries for more information on how the Collector interposes on system library functions.

To preload libcollector.so, you must set both the name of the library and the path to the library using environment variables, as shown in the table below. Use the environment variable LD_PRELOAD to set the name of the library. Use the environment variables LD_LIBRARY_PATH, LD_LIBRARY_PATH_32, or LD_LIBRARY_PATH_64 to set the path to the library. LD_LIBRARY_PATH is used if the _32 and _64 variants are not defined. If you have already defined these environment variables, add new values to them.

Table 3–2 Environment Variable Settings for Preloading the libcollector.so Library

Environment Variable	Value
LD_PRELOAD	libcollector.so
LD_LIBRARY_PATH	/opt/SUNWspro/prod/lib/dbxruntime
LD_LIBRARY_PATH_32	/opt/SUNWspro/prod/lib/dbxruntime
LD_LIBRARY_PATH_64	/opt/SUNWspro/prod/lib/v9/dbxruntime
LD_LIBRARY_PATH_64	/opt/SUNWspro/prod/lib/amd64/dbxruntime

If your Sun Studio software is not installed in /opt/SUNWspro, ask your system administrator for the correct path. You can set the full path in LD_PRELOAD, but doing this can create complications when using SPARC V9 64-bit architecture.

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Note –

Remove the LD_PRELOAD and LD_LIBRARY_PATH settings after the run, so they do not remain in effect for other programs that are started from the same shell.

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If you want to collect data from an MPI program that is already running, you must attach a separate instance of dbx to each process and enable the Collector for each process. When you attach dbx to the processes in an MPI job, each process is halted and restarted at a different time. The time difference could change the interaction between the MPI processes and affect the performance data you collect. To minimize this problem, one solution is to use the pstop(1) command to halt all the processes. However, once you attach dbx to the processes, you must restart them from dbx, and there is a timing delay in restarting the processes, which can affect the synchronization of the MPI processes. See also Collecting Data From MPI Programs.