Conclusions:
1. As stated earlier, persistent connections can dramatically improve overall performance. When using
persistent connections for all transactions, the DB CPU utilization is significantly less than when using
non-persistent connections.
2. For any transactions that run with autocommit turned on, use persistent connections. If the transaction
requires that autocommit be turned off, use of non-persistent connections may be sufficient for pages that
don’t have heavy usage. However, if a page is heavily used, use of persistent connections may be required
to achieve acceptable performance. In this case, you will need a well designed transaction that handles
error processing to ensure no commits are left outstanding.
Database - Isolation Levels
Because the transaction isolation level determines how data is locked and isolated from other processes
while the data is being accessed, you should select an isolation level that balances the requirements of
concurrency and data integrity. DB2_I5_TXN_SERIALIZABLE is the most restrictive and protected
transaction isolation level, and it incurs significant overhead. Many workloads do not require this level of
isolation protection. We did limited testing comparing the performance of using
DB2_I5_TXN_READ_COMMITTED versus DB2_I5_TXN_READ_UNCOMMITTED isolation levels.
With this workload, running under DB2_I5_TXN_READ_COMMITTED reduced the overall capacity by
about 5%. However a given application might never update the underlying data or run with other
concurrent updaters and DB2_I5_TXN_READ_UNCOMMITTED may be sufficient. Therefore, review
your isolation level requirements and adjust them appropriately.
Zend Platform
Zend Platform for i is the production environment that ensures PHP applications are always available,
fast, reliable and scalable on the i platform. Zend Platform provides caching and optimization of compiled
PHP code, which provides significant performance improvement and scalability. Other features of Zend
Platform that brings additional value, include:
y
5020 Bridge – API for accessing 5250 data streams
which allows Web front ends to be created
for existing applications.
y
PHP Intelligence – provides monitoring of PHP applications and captures all the information
needed to pinpoint the root cause of problems and performance bottlenecks
.
y
Online debugging and immediate error resolution with Zend Studio for i
y
PHP/Java integration bridge
By automatically caching and optimizing the compiled PHP code, application response time and system
capacity improves dramatically. The best part for this is that no changes are required to the take advantage
of this optimization. In the measurements included below, the default Zend Platform settings were used.
IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
©
Copyright IBM Corp. 2008
Chapter 6 - Web Server and WebSphere
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