Building the perfect PHP app for the enterprise
Episode 3: Resolving
problems & high availability
Clark Everetts
September 28, 2016

2
Series overview
Now: Resolving problems and high availability
October 13: Optimizing performance (revised date)
Keep users on your site by learning how to use background jobs and caching,
measure performance, and make data-driven decisions.

Clark Everetts
Professional services
Rogue Wave Software

4
Agenda
1. How’s your reputation?
2. Monitoring: Know you have a problem
3. Fault diagnosis / Root cause analysis
4. Optimizing scale: Cluster management
5. Synchronizing session data
6. Conclusion
7. Q&A

How’s your
reputation?

6
The cost of a bad rep
Complexity
Scale
ROI
DIY
Ideal enterprise
Volume
scales
beyond
servers
Performance
degradation
Administrativ
e costs
Not so good reputation
• Page delays
• Application
downtime
Good reputation
• Responsive under load
• Application availability

Monitoring:
Know you have a
problem

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Potential faults
“Issues are discussing, problems are for solving.”
- Me
Fatal
PHP errors
Out of memory
Failed database queries or
updates
Network connectivity
(no connection)
Application
Non-fatal
PHP notices, warnings
Slow functions or request
executions
High memory consumption
Network (degraded)
Application logic

9
The problem with problem resolution
• Most problem resolution time is spent identifying root cause
• Problem reproduction is often difficult and time-consuming
• Many possible sources: server load, input data, database state, etc.

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Problem identification
• Do you know you have a problem?
– Your phone is ringing?
– Getting emails?
– Monitoring tools or services?
• Is a problem brewing that customers don’t see … yet?
Analyze
information
• Debugging
• Logging (files, events
database, application
level logs)
Recreate
problem
With enough relevant
information:
• Reproduce in order to
troubleshoot and verify a
fix
• Can we identify the
cause without having to
reproduce?
Gather
information
• What information can
you collect?

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Monitoring for faults
• Scan log files (not manually!)
– Web server access and error logs
– PHP error log (php.log)
– Application-specific logs (filesystem, database)
• Don’t log noise
• Avoid logging to php.log
• ZendLog, Monolog, error_log()
• Event-based monitoring
– Recorded in event database, visible in UI, accessible via API
– Optional automatic notification via email alerts
– Optional callback URIs for integration with other monitoring tools

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Monitoring events

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Event rules

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Sampling of event types
• Custom event
• Database error
• Function error
• High memory usage
• Inconsistent output size
• Job execution delay/error
• Job logical failure
• PHP error
• Slow function execution
• Slow query execution
• Slow request execution
• Zend Framework exception

15
Example
Results:
Users never experienced a problem
Development team solidified “trust factor” with management
Requirements:
Stale data is unusable data
“Soft” performance criteria
(user’s say when “good enough”)
Problem:
New feature of internal application
suffered slow performance due to
large database result sets from
complex queries.
Challenge:
Prior to rollout, isolate which queries
were experiencing the slowest
response times, make improvements,
& cache results if possible
Used:
Zend Server Monitoring,
IBM i DB2 index analyzer, and
Zend Server Data Cache

Poll #1
How do you discover problems in
your applications?
- Notified by a person (phone call, email, cubicle visit)
- Notified by an in-house automated tool
- Notified by commercial automated tool (Zend, New Relic)

Fault diagnosis /
Root cause analysis

18
Root cause analysis
• Log files
– Can both indicate a problem, and contain necessary diagnostics
• Monitoring tools may provide further info on:
– Failed function call arguments
– High memory consumption
– Etc.
• printf() and var_dump()
• Debuggers (Xdebug, Zend Debugger, phpdbg)
• Code tracing pinpoints in the request execution what triggered the
problem
• Z-Ray: request details right in the developer’s web browser (code trace-
like)

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Event details

20
Debugging

Poll #2
What is your primary means of root
cause analysis?
- printf(), var_dump()
- Logging data to files
- Xdebug
- Zend debugger
- phpdbg

Optimizing scale:
Cluster management

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What is a cluster?

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Why cluster?
• Long-term demand is increasing
– Growing population of mobile devices
– Machine-to-machine traffic (bots, B2B, APIs) on the rise
• Demand is both predictable and unpredictable
– “The Witching Hour” and other periodic processing
spikes
• Resilience when failures occur
Clustering allows you to
• Adapt to changing demand
• Manage infrastructure costs
• Provide redundancy in the face of failures

25
Cluster overview
Requests
Responses

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Cluster characteristics
• Nodes are the same
– Any node can do the same work as all others
– Same specs
• Operating system, installed software base
• Hardware (RAM, disk, etc.)
• Virtual machines
– Containerization and provisioning (Docker, Rocket, Puppet, Chef,
Ansible, SaltStack, Fabric, Capistrano, etc.)
Provides for:
• Scaling out/in as traffic increases/decreases
• Redundancy in the face of failures

Synchronizing
session data

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Load balancing and sessions
Session Affinity
(Sticky Sessions)

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Session clustering

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Session clustering

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Session clustering

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Best practices
How do you know? • Monitoring
How do you diagnose?
• Log files
• Code tracing
• Z-Ray
How do you prevent? • Testing!
• Load balancing
• Clustering
How do you minimize downtime? • Support

Poll #3
How do you currently implement
high availability sessions in a
clustered environment?
- Central database (MySQL, PostgreSQL, Oracle, MariaDB)
- Memcached
- Redis
- Zend Server
- Other/We’re not clustered

34
Conclusion
• Reputation = f(reliability) + f(availability)
• Monitor for faults: know quickly when you have a problem
• Fault diagnosis is all about using the right tools
• Q: Scalability? A: Clustering!
• Sessions in clusters
Visit www.zend.com/en/resources/webinars for webinars
Visit devzone.zend.com for the Zend Developer Zone

Q & A

36
The fastest way to enterprise PHP
Free trial
www.zend.com
• Full, tested, secure PHP stack
• Z-Ray vision deep into your app
• Code tracing
• Job queuing and caching
• Deployment and DevOps
• High availability session clustering
• Backed by support & services

37
Series overview
October 13: Optimizing performance (revised date)
Keep users on your site by learning how to use background jobs and caching,
measure performance, and make data-driven decisions.

38
Don’t miss this premiere PHP event!
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Visit with sponsors 90+ sessions in 6 tracks

39
Watch on demand
• Watch this webinar on demand
• Read the recap blog to see the results of the
polls and Q&A session

Building the perfect PHP app for the enterprise
Episode 3: Resolving
Problems & High Availability
Clark Everetts
September 28, 2016