Sunday, September 9, 2012
Agent framework scalability and Tuning considerations for high volumes
How a Generic Agent works -
A generic Sterling agent is a background batch processing job that does the following -
- Check if there are messages to process from the configured JMS Queue. If the queue is empty post a getJobs message and go to Step 2 else go to Step 4.
- Read the getJobs message and gets the first set of jobs (first batch) from the database using a getJobs method up to the defined buffer size (Number of records to buffer configuration which defaults to 5000).
- Writes these records back into the configured JMS queue in the form of executeJobs messages as well as the next getJobs message containing the last fetched record key such as an TaskQKey
- Retrieves executeJobs messages from the queue and does the necessary processing using the executeJobs method
- After finishing first batch gets the next set of jobs (second batch) up to the buffer size using the last fetched record key in the getJobs message.
- Works on second set of jobs.
- Continue the above process till all the present jobs are worked upon.
- After all the present jobs are worked upon then wait for signal i.e. the agent trigger to start working again.
- Upon getting the signal to start, agent will start working again i.e. follow Step 2 to Step 7
Scalability concerns and Scaling the Availability Monitor agent -
Are Sterling agents multi-threaded?
Not entirely. The getJobs component of the agent working is deliberately made single threaded via the database locking on YFS_OBJECT_LOCK to ensure same set of records are not processed and retrieved multiple times. However, the bulk of the workload is on the executeJobs component which is multi-threaded and can run in multiple JVMs.
Will my agent scale to meet the peak throughput?
Depends on your volumes. Scaling an agent involves tuning the getJobs and the executeJobs component. The scaling and tuning of the executeJobs component is a different exercise which varies depending on the use case so it will not be covered in this post. At low to medium volumes under 100K/hr scalability issue are largely with the executeJobs component. For workloads under 100K jobs/hour the default settings that governs agent behavior should work well. If you are using the agent framework to process over 150K "jobs" per hour there may be challenges using the default implementation. I use the term jobs to denote the message entity for e.g. Jobs in the case of ScheduleOrder are distinct Orders and for Availability Monitor it is distinct Inventory Items.
What are the elements that affect scaling beyond 100K jobs/hour?
- Performance of the getJobs query - Slower the query more time is spent on retrieving messages
- Time taken to write all of the retrieved executeJobs messages to the queue - Default behavior for creating and closing MQ sessions to write individual messages meant that was a significant overhead. Using the product HF to enable bulk loading of messages significantly improves the write time per message. Other aspects such as Persistence setting used for the queue, network latency between the agent servers and MQ server can also affect message write times to the queue.
- Buffer size of messages to get - Default of 5K may not suffice at very high loads as it would mean 40 or more execution of the getJobs component to achieve just 200K throughput. Since getJobs is single threaded there needs to be an optimal number of executions of it.
Scaling the Real Time Availability Monitor (RTAM) Agent - A case study
At a customer site one of the challenges was to scale the Real Time Availability monitor agent to do the Partial Sync of inventory at over 250 K records/hour. The customer was running Sterling 8.5 HF 25, WAS 7 and MQ 7. Following actions were taken to scale the agent from about 150K/hr to around 300K /hr -
1. Tuning the getJobs query - Front loading the YFS_INVENTORY_ACTIVITY table would heavily skew the test results due to the excessive time spent querying it as part of getJobs query. Hence, trimming or keeping the Inventory Activity record table under check significantly alters the time take for getJobs and also more realistically represents production work load. We also ensured usage of the correct index and updated statistics.
2. Setting the agent queue to non-persistent - We defined the internal JMS Queue as non-persistent on MQ. Then, setting the PER(QDEF) option in the scp file for this queue's entry while generating the bindings. Writing each message to the persistent queue takes between 11-20ms whereas on the non-persistent queue it is under 5 ms.
3. Enabled JMS session pooling for this agent via the following property in customer_overrides.properties -
yfs.yfs.jms.session.disable.pooling=N
This allows sessions to be borrowed and returned to the pool instead of new ones getting created and closed for each message.
yfs.agent.bulk.sender.batch.size=50000
The batch size setting of 50000 should be equal to or great than the maximum buffer size you plan to use across all agents.
Agent vs Integration Server in Sterling Order Management System
Agent Vs Integration Server : Processes that run in the background to perform various tasks.
Even though both servers performs background activities has below differences
| AGENT SERVER | INTEGRATION SERVER |
|---|---|
| The process that runs the time-triggered transactions is known as an agent server. | An Integration Server is a process that manages asynchronous services, such as messages to and from external systems. |
| Multi-thread : Supported | Multi-thread : Supported |
| Multiple instances : Support | Multiple instances : Support |
| Can run multiple time triggered transaction: Yes | Configured via Service Definition Framework |
How to create Agent Server in Sterling Order Management System ?
- Go under any time triggered transaction
- Click the green color + symbol under “Agent Criteria Definition”section
- Enter Server name and click save
How to create Integration Server in Sterling Order Management System ?
- Go under “Service Definitions” create new service
- Drag and drop JMS or file component
- Connect the component with any other component (For example email or export_db)
- Click on the connector as shown in below image
- Go under server tab
- Click the green color + symbol
- Enter Server name and click save
How to find server is Agent Server or Integration Server ?
This information is available in yfs_server table. We can find using below query.
select server_type from yfs_server where servername=’?’;
Server type :
- 00 – Integration Server
- 01 – Agent Server
Time-triggered transactions
A time-triggered transaction is a program that performs a variety of individual functions, automatically and at specific time intervals. It is not triggered by conditions, events, or user input.
- Automatically : Schedule Trigger message every N minutes (Configuration under time triggered transaction)
- Manually: Trigger from $U process; triggeragent.sh <Criteria Name>
Three types of time-triggered transactions
- Business process transactions – responsible for processing day-to-day transactions. Example RELEASE.0001
- Monitors – watch and send alerts for processing delays and exceptions. Example ORDER_MONITOR_EX
- Purges – clear out data that may be discarded after having been processed. Example SUPPLYTEMPPRG
Good question. That task_q entry decision is made by pipeline transaction configuration. This configuration available under transactions Others tab. Look for This transaction is task based checkbox. if this checkbox selected an entry will be made to yfs_task_q table. For example
Create order next transaction is schedule order. Schedule order has “This transaction is task based” enabled. So during order creation when order moved to created status system finds what is next transaction and if the transaction enabled for task_q. if yes entry made into yfs_tak_q table.
Hope this helps. if not clear please write to us. Thanks
yantra/yfsadmin/agenttrigger.jsp
OMS Log File Locations
Development server log files all reside on vldvoms01.lifetouch.net but the paths vary by environment.
- Foundation/logs/
OMS3 MC log files can be found on the following servers in the Foundation/logs/ directory. OMS3 QA log files can be found on the following servers in the Foundation/logs/ directory. OMS3 Prod log files can be found on the following servers in the /Foundation/logs/ directory.
Agent Trigger
Yantra agents trigger themselves on a regular basis. However, if you need to trigger an agent immediately, the following web page will let you select an agent and trigger it.
OMS Agent Server Descriptions
"Agent Servers" are java processes that contain one or more process "Agents" that move work through the Sterling framework. Note that "Agent Servers" are commonly referred to as "Agents" for short. They are a core part of Spectrum OMS.
OMS Agent Server 'HOW TO' Instructions for Starting / Monitoring
Agents are multi-threaded, stand-alone processes that process work within the Sterling Commerce framework. Integration Servers are a special class of Agents that are used to send and receive messages from other applications.
Use the Sterling System Management Console to view the list of currently running agents. To open the management console, login to OMS / Spectrum, select the "System" menu, and then select the "Sterling System Management Console" sub-menu.
Once the management console is open, select the "Tools" menu and then the "View Live Agents / Integration Servers" sub-menu. In addition to viewing the live Integration Servers, you can stop or suspend the servers from the console. Use "./stopagents.sh stop" to stop the agents.
If you need to start an Agent / Integration Server in TEST or SIT, cat the content of the /bin/startServer.sh file. Find the agent line that you need and copy/paste the line in your ssh session.
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