ColdFusion Performance Tuning Keen Haynes Certified ColdFusion Developer

ColdFusion Performance

Tuning

Keen HaynesCertified ColdFusion Developer

Overview Application Environments Testing Techniques Tuning Techniques Coding Tips Variable Locking Databases and Queries Thread Processing Debugging

Application Environment Goals

Provide separate, autonomous areas for Development, Testing/Staging and Production

Provide the Developer Community with an environment that maximizes

Productivity Effectiveness

Application Environment, cont. Provide a Testing/Staging environment that facilitates

Automated application staging Testing Load/Scalability testing Production readiness (data migration, etc)

Provide a Production environment that is Scalable Manageable Makes efficient use of resources Designed for High-Availability and end-user

responsiveness

Testing Techniques

Perform “Critical Path” or “Strategic Strike” Analysis

Stress User vs. Real User Build a “Real-World” load generator test script Load Test & Perform Bottleneck Analysis Do Manual Timings in a browser (no load vs

under load) Perform Endurance Testing Examine log files during testing

Testing Techniques, cont. Principle elements involved in template response time:

Total Execution Time (i.e. 203ms) Query Time (i.e. 156ms) Processing/Response Time: Total - Query (i.e.

46ms)

Tuning Techniques

Establish your max user base line Manually walk through test and capture

explode bench marking – identify bottlenecks

Test with new general CF admin settings Test with changes to simultaneous

request settings changes – normally the biggest bang for your buck.

Managing Performance, cont. Query Time:

Can be significantly reduced by proper DB Design, Configuration, Tuning and Administration

Use a professional Database Administrator (DBA) Ensure/verify updated/proper version of ODBC (i.e.

MDAC v 2.6) and/or DB client libraries on CF Server In CF Server, try “Maintain DB Connections” (Very) generally, queries taking longer than > 150ms

execution time w/no load MUST be examined closely

Coding Tips

Use CF built-in functions wherever possible Avoid complex logic inside CFQUERY (build

outside) Fully scope variables Lock all Session, Application, and Server variable

access MDAC update

ComCheck

Overuse of #

Coding Tips Carefully load test and analyze CFX calls response

times C++, Java

Be careful using CFHTTP, CFFTP Scalability of CFFILE CFMAIL in mass mailings Avoid redundant queries and looping queries Use Stored Procedures where appropriate Avoid redundant code

Use of CFINCLUDE versus Custom Tags

Blank space

Coding Tips Caching strategies

Queries Administrator CACHEDWITHIN Selection of content

Templates Administrator CFCACHE SUPERCACHE

Variable Locking

Server, Application, and Session vars must be locked using <CFLOCK>!

Or random memory corruption occurs. Consider Client and Request scopes Symptoms: PCode errors, Unknown

Exception errors Use “Full Checking” in Dev and

Staging environments

Variable Locking

Levels: Exclusive, ReadOnly Exclusive: does not allow any operations on a

given variable scope until the current process within the lock is complete.

ReadOnly: allows multiple reads within the scope but no write access.

If an Exclusive lock is processed at the same time as a ReadOnly lock, the ReadOnly lock will wait for the Exclusive lock to finish before proceeding.

Variable Locking Locking methods

As a general rule of practice locking should be done in the code using CFLOCK.

ReadOnly locking can be applied globally to SERVER, APPLICATION, and SESSION variables using the "Automatic Read Locking" option on the Locking page of the ColdFusion Administrator.

There is no method to write-lock variables globally in the CF Administrator when using multi-threaded sessions. One could single-thread sessions using the "Single Threaded Sessions" option, thereby eliminating the need for locking SESSION variables, but this results in severe performance degradation and is not recommended for scalable applications.

Variable Locking CFLOCK Syntax

Typical usage

<cflock SCOPE="Application", "Session", or "Server" TIMEOUT=#seconds TYPE="Exclusive", or "ReadOnly">

[process] </cflock>

Variable Locking NAME Locks

May be used in place of locking by scope. The NAME argument is used in place of the SCOPE

argument.

Nesting Locks As a general rule of thumb, nested locks should be avoided

as they can result in deadlocks. Please refer to the CFML Language Reference Documentation if nested locks are considered absolutely necessary.

Avoid use of locks in queries

Database Issues

Use latest stable release Look for PCode errors including “SQL” or

“Query” Queries that never return; apparent CF

Server hang Troubleshoot by setting max DB

connections to 1

SQL

Ensure appropriate indexes are available for all common queries

Clustered Indexes in SQL Server Avoid calling queries in loops Use joins instead of looping around

queries if possible

Query Caching

Appropriate for queries with few permutations

Limits to number and size of queries No easy way to “flush” cached

queries Caching for only one minute at 10

queries per second reduces load on the database (for that query) by 600x

Query Caching

Example: Cache statecodes query for 10 minutes:<CFQUERY Name=“qStateCodes” DataSource=“#Request.DSN#” CachedWithin=“#CreateTimeSpan(0,0,10,0)#”> SELECT * FROM States ORDER BY StateCode<CFQUERY>

A .cfm page is requested by a web browser

The .cfm request passed to the CF Web server stub

The stub sends the request to the ColdFusion Application Server for processing.

Thread Processing

Thread Processing (cont)

A listener thread receives the request, sends it to one of the waiting active simultaneous threads to process the request. If all of simultaneous threads are busy, the listener

thread places the request on a waiting list. When one of the simultaneous request slots becomes

available, listener thread sends the waiting request to the active slot.


The ColdFusion server Processes all of the CFML tags in the page Converts the results to HTML and sends them back

to the web server to be sent to the browser.


The thread is put back into the active pool to be reused. Much less resource intensive than the thread

create/destroy scenario.

3rd Party Calls

If 3rd party call never returns a result set or error message, thread will continue to wait and will NOT timeout If many .cfm page requests with blocking third party

requests Simultaneous Request limit will be reached ColdFusion server will appear to hang

BUT: ColdFusion is not failing to process, it simply is waiting for a response from a third party resource call.

ColdFusion Debugging Performance or stability problems more often than not

are caused by processing of a third party request Pinpointing these third party problems can be difficult

The following steps should be taken to help determine the source of the issue

ColdFusion Debugging STEP 1

Examine logs


Verify the source of the unresponsiveness of the ColdFusion server

Try opening up ColdFusion Administrator or other simple .CFM page

If this fails, try to open a .html or .html page If web server returns the .html page, the web server is

functioning properly, go to Step 2 If .html page does not return, web server is causing the

problem, stop and restart the web server If after stopping and starting the web server ColdFusion

pages still do not return, go to step 2.


Open up the NT Performance Monitor or run cfstat and add the CF "Queued Requests", and "Running Requests" counters, along with %CPU usage for the CFSERVER instance.

If third party request is suspected, at time of the hang: %CPU usage will be approx. zero, Running Requests will be approx. at Simultaneous Request limit and Queued Requests should be rising

ColdFusion Debugging STEP 4 - At the time of the unresponsive period, try

running a query through MSQuery using SQLPlus or ISQL. These do not connect to the database through ODBC and will

verify the ODBC connection to the database

Run the same SQL statement that you believe is causing the problem

SQL Profiler

Deadlocking

ColdFusion Debugging

STEP 5 - Turn on "logging of slow pages" in the debugger section. At the very least it will list the templates that are active for n

seconds.

This will give your users a place to start looking for long running queries


STEP 6 - Non-functioning, or slow functioning CFX tags, or CFML code called in your ColdFusion templates can also be the cause of ColdFusion performance/stability issues.

Determining that a CFX tag or piece of CFML code is causing the problem is not an easy task

Use the CF function GetTickCount() around CFX tag call (or any suspected piece of slow performing code)


Example:

<CFSET tickBegin = GetTickCount()>

(code to be timed here...)

<CFSET tickEnd = GetTickCount()>

<CFSET totalTime = tickEnd - tickBegin>

<CFOUTPUT>Time to Complete: #totalTime#</CFOUTPUT>


Versions: Be certain all patch revisions are current

OS Kernal C++

DB WWW CFAS


Poorly written SQL statements Full table scans (not, like)

No database indexing No use of stored procedures Deadlocking


CFMAIL as mass-mailer CFX tags that lose thread control CFHTTP - incorrect URLs No CFLOCK around client, application

variables Poorly written logic Liberal use of CFLOCATION Disk I/O


Logs Overuse (CFAS) Fill disk (DB, WWW, CFAS)

Client variable storage in registry Debug settings on

IP specific

Third party application servers sharing box Extraneous services

ScreenSaver, etc.

Documents

ColdFusion Performance Tuning Keen Haynes Certified ColdFusion Developer