This document discusses troubleshooting APEX applications. It describes how to enable debugging and tracing in both develop and runtime modes. It also covers logging APEX activity and examining logs to diagnose performance issues. The example problem discussed was an application making excessive calls to retrieve images from the database, slowing it down. The solution was to move the images to a web server to leverage caching.

1. Copyright © 2013 Apex Evangelists
Troubleshooting APEX
Applications
Nienke Gijsen en Roel Hartman

2. About Roel
• Director of APEX Evangelists NL
• 20+ years of Oracle Experience
• “RoelH” in the APEX Forum
• Presenter at KSCOPE, OOW, Collaborate, DOAG, UKOUG, ...
• Oracle ACE Director
• Blog @ http://roelhartman.blogspot.com
• Twitter : @RoelH

3. Enterprise Manager

4. Alert.log
• Twee tot drie keer per week
• Apex process
• ORA-04030: out of process memory when trying to allocate 82456
bytes (pga heap,control file i/o buffer)
• ORA-04030: out of process memory when trying to allocate 16328
bytes (koh-kghu sessi,pmucalm coll)

5. Trace File
PRIVATE HEAP SUMMARY DUMP
15 GB total:
15 GB commented, 183 KB permanent
81 KB free (0 KB in empty extents),
15 GB, 1 heap: "session heap "
declare
rc__ number;
simple_list__ owa_util.vc_arr;
complex_list__ owa_util.vc_arr;
begin
owa.init_cgi_env(:n__,:nm__,:v__);
htp.HTBUF_LEN := -1;
null;
null;
simple_list__(1) := 'sys.%';
simple_list__(2) := 'dbms_%';
simple_list__(3) := 'utl_%';
simple_list__(4) := 'owa_%';
simple_list__(5) := 'owa.%';
simple_list__(6) := 'htp.%';
simple_list__(7) := 'htf.%';
simple_list__(8) := 'wpg_docload.%';
if ((wwv_flow_epg_include_modules.authorize('wwv_flow_file_mgr.get_file') = false) or (owa_match.match_pattern(p_string =>
'wwv_flow_file_mgr.get_file'

6. Metalink
PLSQL Procedure Causing ORA-04030: (pga heap,control
file i/o buffer) And ORA-04030: (koh-kghu sessi,pmuccst:
adt/record) or ORA-04030: (koh-kghucall ,pmucalm coll)
Errors [ID 1325100.1]
Solution
• Change the page count at the OS level:
• $ more /proc/sys/vm/max_map_count
$ sysctl -w vm.max_map_count=262144 (256K)

7. Apex Developers
• Error log
• Tijdstippen onderzoek
• Wat doet de get_file?
• Wat kan er 16GB groot zijn?

8. En
nu?
DBA

9. Troubleshooting APEX Applications
Debugging Tracing Logging

10. Debugging APEX Applications

11. Debugging APEX Applications
• Develop Mode
• Runtime Mode
• Websheets needs a Development environment !
• @apxdvins.sql / @apxdevrm.sql

12. Debugging Enable - Develop Mode
• Application Level Setting

13. Debugging Enable - Runtime Mode
begin
wwv_flow_api.set_security_group_id(p_security_group_id=>2616513429239104);! !
wwv_flow_api.set_enable_app_debugging(103,1);
end;
Workspace ID
Application ID
1 = ON
0 = OFF

14. Debugging - Develop Mode

15. Debugging - Runtime Mode
LEVEL1 ..
LEVEL9

16. Debugging - Instrumentation
apex_debug

17. Remote Debugging
• Using SQL Developer

18. Tracing APEX Applications

19. Tracing Enable - Develop Mode
• Workspace Level Setting (default “Yes”)

20. Tracing Enable - Runtime Mode
begin
apex_instance_admin.set_parameter( p_parameter => 'TRACING_ENABLED'
, p_value => 'Y' );
end;
SYS, SYSTEM, APEX_040200 or APEX_ADMINISTRATOR_ROLE

21. Tracing - Develop & Runtime Mode
DEBUGGING must be enabled as well!

22. Logging APEX Applications

23. Logging Enable - Develop Mode
• Workspace Level Setting (default “U”)
• Application Level Setting (default “Yes”)

24. Logging Enable - Runtime Mode
• Workspace Level Setting (default “U”)
begin
apex_instance_admin.set_parameter( p_parameter => 'APPLICATION_ACTIVITY_LOGGING'
, p_value => 'U' ); -- or [A]lways, [N]ever
end;
• Application Level Setting (default “Yes”)
begin
wwv_flow_api.set_security_group_id(p_security_group_id=>2616513429239104);!
wwv_flow_api.set_logging(103,‘YES’); -- Or ‘NO’ to switch it off
end;

25. Logging - Where Is It Going?
SELECT apex_view_name, comments
FROM apex_dictionary
where column_id = 0
AND apex_view_name LIKE '%LOG%'
•

26. Logging - How Long Is It In There?
• Workspace Level Setting
• Develop Mode
• Runtime Mode
begin
apex_instance_admin.set_log_switch_interval
( p_log_name in 'ACTIVITY' -- or ‘ACCESS’, ‘CLICKTHRU’, ‘DEBUG’
, p_log_switch_after_days => 180 ); -- between 1 and 180, default 14
end;
• Rotating Logs

27. Logging Examining - Develop Mode

28. Logging Examining - Runtime Mode
select application_id
, page_id
, to_char(view_date, 'DD-MM-YYYY HH24:MI') datetime
, log_context
, elapsed_time
, rows_queried
from apex_workspace_activity_log
order by elapsed_time desc

29. The Results
• Fluctuating Performance (avg 0.1 - max 1000 sec)
• Calls to WWV_FLOW_FILE_MGR.GET_FILE
• Used to retrieve images from the database

30. The Cause
•SELECT ‘<img src=”#WORKSPACE_IMAGES#no_picture.jpg”>’ ...
FROM <awesome join>
WHERE <more or less restrictions>
• Calls WWV_FLOW_FILE_MGR.GET_FILE tons of time
to retrieve ... nothing ....

31. The Solution
• Moved all images (and CSS / JavaScript) to web server
• Replaced ‘<img src=”#WORKSPACE_IMAGES#no_picture.jpg”>’
with ‘<img src=”/my_img/no_picture.jpg”>’
• Now using web server caching
• Database isn’t suffering from millions of calls anymore

32. Copyright © 2013 Apex Evangelists
http://apex-evangelists.com
Q& A

33. roel@apex-evangelists.com
http://apex-evangelists.com