Optimizing Your Visual COBOL Applications Darren ... - Micro Focus

Optimizing Your Visual COBOL 

Applications 

Darren Self & Chris Glazier 

Micro Focus

Performance matters because… 

2

Agenda 

• Locating Bottlenecks 

• Tuning your Files and the 

File Handler 

• Configuring OpenESQL 

Database Access 

• Optimizing Your 

Application 

3

Out of the Box Performance

Finely Badly 

Tuned

The choice is yours…

Locating the Bottlenecks 

• Visual COBOL Profiler 

– Native code 

– Report at COBOL 

source level 

• Visual Studio Profiler 

– Managed code 

– Report at method level 

7

Visual COBOL Profiler 

• 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 Studio Profiler 

• 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

Tuning Your Files and the File Handler 

• Access Permissions 

• File Definition - Keys 

• Fine Tuning EXTFH.CFG 

10

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

Access Permissions – Sharing Modes 

• Can be specified in SELECT: 

or 

select test-file assign to “testfile.dat” 

… 

sharing with |all other| 

|no other|. 

lock mode is exclusive. 

• Can be specified on OPEN: 

open i-o sharing with |all other | test-file 

|no other | 

|read only|.

Access Permissions - READ 

Time Taken to Read Records 

Exclusive Access Allow Readers Allow All Others 

2 mins 2 secs 4 mins 23 secs 8 mins 40 secs 

Reading 8,000,000 records from IDX Format 8 file 

Sequentially

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 

2 Alternate 

Keys 

Time Taken to Create File 

Number of 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

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

Compression 

Sequential 

WRITE 

Random 

READ 

Sequential 

READ 

Compression Type 

None Data Data + Keys 



2 mins 04 secs 2 mins 46 secs 2 mins 50 secs

It doesn’t help…

Neither does this…

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

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

INDEXCOUNT 

2 alt keys 3 alt keys 

5 min 48 secs 6 min 19 secs 

Time Taken to Create File 

4 alt keys 5 alt keys 

6 min 29 secs 7 30 mins min 32 6 secs 

8 million records, 5 alternate keys, resulting file 5GB

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

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

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

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

Configuring OpenESQL Database Access 

• Database Drivers 

• OpenESQL Behavior Directive 

26

Database Drivers 

• 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

OpenESQL Behavior Directive 

• 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

Optimization Demo

Optimizing Your Application 

• Application Structure 

• Program Structure 

• Data 

• Code 

30

Application Structure 

• It’s important! 

• Execution formats 

• Modularity 

31

Execution Formats 

• 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

Communicating 

• 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

Demo - Execution Formats

Managed code boundary 

• Compiled for JVM 

– Uses JNI 

– Notoriously slow 

• Compiled for .NET 

– Uses Platform Invoke 

– Minimal overhead 

36

Program Structure 

• Independent procedures 

• Logical separation of functionality 

• Use sections/paragraphs consistently 

37

In Micro Focus, the guidelines are... 

• 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

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

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

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.

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 ref-a pic x(2) comp-5. 

03 loc-a pic x comp-5. 

• Aligned table item 

01 tbl2 occurs 200. 


03 ref-a pic x(2) comp-5. 

03 loc-a pic x comp-5. 

03 pic x.

Demo - Alignment Issues

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

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

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

Demo – Arithmetic Issues

Your Mission... 

• Identification 

• Awareness 

• Resolution 

• Communication 

– http://community.microfocus.com

Performance may feel like this...

When it should be like this...

Some Useful Checker Directives 

noalter 

noseg 

noqualproc 

noimplicitscope 

nocheck 

Improves checker speed 

Improves checker speed. Catches use of 

identical, and confusing, paragraph names 

Enforce use of scope delimiters 

Catch subtle bugs early 

Turn off run time checking

Some useful NCG Directives 

nocheck 

lnkalign 

opt 

litlink 

linkalias 

Turn off run time checking, including 

subscript, linkage and divide-by-0 checks 

Assert that linkage items aligned 

Generates faster code 

Turn on global optimisations. Generates 

faster code, but takes longer to generate 

Ensure calls are linked rather than 

dynamically bound 

Specify aliasing of linkage items

@microfocus or hashtag #devcon2013 

Follow us on LinkedIn or join the group 

Connect with your peers on the Community

Optimizing Your Visual COBOL Applications Darren ... - Micro Focus

Create successful ePaper yourself

Delete template?

Save as template?