Attaching to a running program
It is possible to start the debugger for a program running on the same computer.
Basics
Use the fgldb command with the -p pid
option, to switch an fglrun process running on the same computer into debug
mode.
The fgldb command must be executed on the machine where the fglrun process executes.
Tip: The graphical debugger of Genero Studio is able to start the
fgldb tool on another computer through ssh, so that it is possible to debug a
program running on a remote machine. See Genero Studio documentation for more details.
The fgldb command line tool takes the fglrun process id
as value for the -p
argument.
Note: Before starting a debug session, make sure that you fulfill the prerequisites for debugging.
Debug a program running on a UNIX server
First, identify the process id of the fglrun program running on your server.
For example, on a UNIX®
platform, use the ps
command:
$ ps a | grep fglrun
10646 pts/0 S+ 0:00 /opt/myapp/fgl/lib/fglrun stockinfo.42m
Note: Inspect the GAS log files to find the id of a fglrun process running behind a GAS
application server. Enable full log reports in the GAS to get detailed information about process
execution.
You may want to debug processes that use a lot of machine resources (processor, memory or open files). Use a system utility to find a process id by resources used (for example, the top command on Linux®).
Execute the fgldb tool with the process id of the program you want
to attach
to:
$ fgldb -p 10646
108 DISPLAY ARRAY contlist TO sr.*
(fgldb)
The
(fgldb)
prompt indicates that you are now connected to the
fglrun process, and the program flow is suspended. To continue with the program
flow, enter the "continue
" debugger
command:(fgldb) continue
Continuing.
The application will then resume. To suspend the program again and enter debugger
commands, press CTRL-C in the debug console. fgldb will display
the interrupt message and return control to the
debugger:
...
Continuing.
^CINTERRUPT
108 DISPLAY ARRAY contlist TO sr.*
(fgldb)
At this point, you can enter debugger commands. For example, set a break point and
continue until the break point is
reached:
(fgldb) b 427
Breakpoint 2 at 0x00000000: file contacts.4gl, line 427.
(fgldb) continue
Continuing.
Breakpoint 2, edit_contact() at contacts.4gl:427
427 IF new THEN
(fgldb)
To finish the debug session, close the connection with the "
detach
"
debugger
command:(fgldb) detach
Connection closed by foreign host.