7. • Visual COBOL Profiler
– Native code
– Report at COBOL
source level
• Visual Studio Profiler
– Managed code
– Report at method level
7
Locating the Bottlenecks
8. • Works with native code
• Compile with PROFILE directive
• Run application to generate .prf
• Run Profiler to create report
• What information does it provide?
– Gives the total execution time
– By section and paragraph
8
Visual COBOL Profiler
9. • Integrated with Visual Studio IDE
• Works with .NET managed code
• Allows comparison of profiling data
between different runs
• What information does it provide?
– Gives total execution time by module
– Shows hot code execution paths
9
Visual Studio Profiler
10. • Access Permissions
• File Definition - Keys
• Fine Tuning EXTFH.CFG
10
Tuning Your Files and the File Handler
11. Access Permissions
• Examine your data files on a per-file basis.
– How are they being used?
• When opening files:
– Don’t just use open I-O for everything
– Use exclusive access where possible
– Otherwise, allow only readers
– Only where absolutely necessary, give
all others complete access to the file
12. Access Permissions – Sharing Modes
• Can be specified in SELECT:
select test-file assign to “testfile.dat”
…
sharing with |all other|
|no other|.
or
lock mode is exclusive.
• Can be specified on OPEN:
open i-o sharing with |all other | test-file
|no other |
|read only|.
13. Access Permissions - READ
Reading 8,000,000 records from IDX Format 8 file
Sequentially
Time Taken to Read Records
Exclusive Access Allow Readers Allow All Others
2 mins 2 secs 4 mins 23 secs 8 mins 40 secs
14. File Definition - Keys
• If you don’t use it, then lose it! – each key needs
to be updated for each insert and delete.
• Shorter the key the better – fit more in a node
Time Taken to Create File
Number of Alternate Keys
2 Alternate
Keys
3 Alternate
Keys
4 Alternate
Keys
5 Alternate
Keys
5 mins 48 secs 6 mins 19 secs 6 mins 29 secs 30 mins 06 secs
File size
2 alternates = 4,908,620,800
3 alternates = 5,172,377,600
4 alternates = 5,500,134,400
5 alternates = 5,763,891,200
15. File Definition - Compression
• Data compression
– Minimal performance hit
• Index compression
– Always a performance hit, sometimes severe.
– File Handler must sequentially search entire
node when looking for a key
16. Compression
Compression Type
None Data Data + Keys
Sequential
WRITE
5 mins 35 secs 5 mins 45 secs 9 mins 50 secs
Random
READ
3 mins 34 secs 3 mins 46 secs 4 mins 56 secs
Sequential
READ
2 mins 04 secs 2 mins 46 secs 2 mins 50 secs
19. Fine Tuning the File Handler – EXTFH.CFG
• Options must be set in a configuration file
set EXTFH=c:extfh.cfg
Can be set in Visual Studio
app.config file
• Set on a per file basis
– INDEXCOUNT
– NODESIZE
– LOADONTOHEAP
20. INDEXCOUNT
• Specifies the number of index nodes to be cached for an
index file. - Default cache size used is now 32 nodes.
• Use when writing files where there are multiple keys
• Use when reading files randomly
• Reading files – sequentially may degrade performance
• Ideal INDEXCOUNT = (Max Tree Depth * No. keys) + No. keys
– Use rebuild /f - to find max tree depth
[XFH-DEFAULT]
[file1.dat]
INDEXCOUNT=42
21. INDEXCOUNT
8 million records, 5 alternate keys, resulting file 5GB
Time Taken to Create File
2 alt keys 3 alt keys 4 alt keys 5 alt keys
5 min 48 secs 6 min 19 secs 6 min 29 secs 7 mins 32 secs30 min 6 secs
22. NODESIZE
• The NODESIZE option specifies the size of the
index nodes to use for an indexed file when it is
created.
• NODESIZE={512|1024|4096|16384}
• Use when reading records sequentially
• Avoid using with INDEXCOUNT set high
[XFH-DEFAULT]
[file1.dat]
NODESIZE=4096
23. NODESIZE – Reading Records
NODESIZE Sequential Access Random Access
1024 3 mins 55 secs 3 mins 09 secs
4096 3 mins 03 secs 4 mins 01 secs
16384 1 mins 59 secs 4 mins 27 secs
24. LOADONTOHEAP
• Forces the File Handler to load an entire file
onto a memory heap
• All file operations execute in memory, only
writing back to disk when it is closed
• Use only in exclusive mode
• Use only on small files
• Use with caution- Speed vs Data Integrity!
[XFH-DEFAULT]
[file1.dat]
LOADONTOHEAP=ON
25. File Handling Summary
• Consider tuneables on a file-per-file basis
• Think about permissions.
Can you use exclusive access?
• Avoid key compression if possible.
• Random access – calculate the optimum
INDEXCOUNT figure with rebuild /f
• Sequential access – look at NODESIZE
• Small exclusive files – look at LOADONTOHEAP
27. • Drivers to use
– ODBC = Native Code
– ADO = Managed .NET
– JDBC = Managed JVM
• SQL Server - ODBC vs Native Client
– Do NOT use old SQL Server ODBC drivers
– Use SQL Server Native Client 10.0 or higher
• Oracle – ADO
– Use Oracle Data Provider ODP.NET
– Do not use Microsoft’s Oracle Client driver
27
Database Drivers
28. • SQL(BEHAVIOR=MAINFRAME) – Fastest
– data access for cursors is read only for all by default
– SQL Server uses firehose cursors, Oracle and DB2 use block fetches
• SQL(BEHAVIOR=ANSI) – Medium Fast
– data access for cursors is updateable for all by default
– SQL Server uses firehose cursors, Oracle and DB2 use block fetches
• SQL(BEHAVIOR=UNOPTIMIZED) – Slowest
– data access for cursors is updateable for all by default
– no block fetching done
– compatible with older MF products
• esqlconfigw utility - Set default BEHAVIOR directive for system
28
OpenESQL Behavior Directive
32. • INT code
– Slow, portable, dynamically loaded, not shared
• GNT code
– Fast, dynamically loaded, not shared
• Object code
– OS defined format, not directly executable
– Basis for native executable formats (exe, dll etc)
– More efficient than .gnt
• Managed code (IL, JVM)
– Third party managed environment
– Portable and interoperable on that framework
32
Execution Formats
33. • PERFORM - very fast
– Acts locally, potentially on all data
– Does not take parameters
• CALL - slower
– Called code is external
– Takes parameters
– Only those parameters are affected
33
Communicating
36. • Independent procedures
• Logical separation of functionality
• Use sections/paragraphs consistently
37
Program Structure
37. • Do...
– Use SECTIONs
– PERFORM these sections
– Use GOBACK rather than EXIT PROGRAM
• Don’t...
– Use PERFORM THRU or PERFORM paragraphs
– Use inter-section GOTOs
– Use alter, segments, OSVS or RM PERFORM-STYLE
38
In Micro Focus, the guidelines are...
38. A Word on ‘In line Perform’s
• Excellent structured programming technique
• Keep the loop condition simple
– Remember it’s tested each iteration
• Avoid ‘goto’s out of the loop
– Code generator optimises well structured, single exit loops
– Easier to understand
– Avoid problems when moving to managed code
39. Data - Alignment
• Memory organised into 4 or 8 byte words
• Access across word boundaries is slow
– At least twice as slow
– Up to 50 times slower
• Access across word boundaries gives larger code
– Nine extra instructions for a 4 byte item
on Itanium machines
40. Data – Alignment Example
• This comp-5 item count-a is aligned
01 grp-item.
03 count-a pic x(4) comp-5.
03 ch pic x.
• This comp-5 item count-b is not aligned
01 grp2-item.
03 ch2 pic x.
03 count-b pic x(4) comp-5.
41. Data – Alignment Example in Tables
• The stride of a table should be a multiple of 4
– Pad the table to ensure this is true
• Misaligned table item
01 tbl1 occurs 200.
03 count-a pic x(4) comp-5.
03 ref-a pic x(2) comp-5.
03 loc-a pic x comp-5.
• Aligned table item
01 tbl2 occurs 200.
03 count-a pic x(4) comp-5.
03 ref-a pic x(2) comp-5.
03 loc-a pic x comp-5.
03 pic x.
43. Data Types - Numerics
• Optimal is 4 byte integer comp-5
– Signed or unsigned, but try not to mix in same statement
• 1, 2 or 8 byte OK if required
• Advantages
– Smaller faster code
– Required for some APIs
– Quicker to generate
44. Data Types – Managed
• Specify managed types whenever possible
– binary-long or float instead of COMP-3 or DISPLAY
– Use at 01 level
• no group items where possible
– Use types instead of COBOL PICs
• Managed code directives
– ILEXPONENTIATION”FLOAT” for exponentiation speed
45. Code - Arithmetic
• Use operands of same type
• Two operand style is always efficient
– add a to b
– divide c into d
• Compute statement without divide operations
– Split into separate COMPUTE and DIVIDE statements
• Avoid using the ON SIZE error
51. Some Useful Checker Directives
Enforce use of scope delimiters
Catch subtle bugs early
noimplicitscope
Turn off run time checkingnocheck
Improves checker speed. Catches use of
identical, and confusing, paragraph names
noqualproc
Improves checker speed
noalter
noseg
52. Some useful NCG Directives
Specify aliasing of linkage itemslinkalias
Ensure calls are linked rather than
dynamically bound
litlink
Turn on global optimisations. Generates
faster code, but takes longer to generate
opt
Assert that linkage items aligned
Generates faster code
lnkalign
Turn off run time checking, including
subscript, linkage and divide-by-0 checks
nocheck
53. @microfocus or hashtag #devcon2013
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