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Administering
Administer the product by using the Teracloud® Streams graphical user interface, APIs, or the streamtool command-line interface.
Jobs
You can start and administer jobs by using Streams Console or the streamtool command-line interface.
Enabling resource load protection for Teracloud® Streams instances
The resource load protection option controls whether overload protection is enabled as determined by the values of three metrics: CPU utilization, memory utilization, and network bandwidth utilization. When you enable resource load protection, Streams prevents additional work (new PEs) from being placed on an overloaded resource.

Welcome
Learn about the core capabilities of Teracloud® Streams, its architecture, and key concepts.
Installing
Use this information to install, upgrade, and uninstall the Teracloud® Streams product.
Configuring
Create a basic or an enterprise domain which is a single point for configuring and managing common resources, security, and instances.
Administering
Administer the product by using the Teracloud® Streams graphical user interface, APIs, or the streamtool command-line interface.
- Domains
  After you create a Teracloud® Streams domain, you can administer it by using the Streams Console graphical user interface and the streamtool command-line interface.
- Resources
  After you add resources to domains and instances, you can administer them by using the Streams Console or the streamtool command-line interface.
- Instances
  To create and manage instances, you can use the Streams Console or the streamtool command-line interface.
- Domain and instance services
  Before you can perform Teracloud® Streams tasks, Teracloud Streams domain and instance services need to be running on resources in the domain. Domain services are started by starting the domain and instance services are started by starting the instance.
- Jobs
  You can start and administer jobs by using Streams Console or the streamtool command-line interface.
  - Job names and identifiers
    A job name is a name that you specify when you submit a job. Teracloud® Streams also assigns a job identifier (ID).
  - Using application configuration objects to access secure data
    You can use application configuration objects to access securely stored configuration data from your Teracloud® Streams environment.
  - Submitting jobs
    To start a stream application in Teracloud® Streams, you submit an application bundle to a started instance that creates a job.
  - Modifying running jobs
    You can change a running job by running the streamtool updateoperators command and supplying the parameters that you want to change either with the command options or by specifying a job configuration overlay file that includes the parameters that you want to change. You can also use Streams Console.
  - Monitoring jobs
    Use the Streams Console or streamtool commands to view the status of application jobs in a Teracloud® Streams instance.
  - Monitoring processing elements
    Use the Streams Console or streamtool commands to view the status of processing elements (PEs) in a Teracloud® Streams instance.
  - Capturing the job topology for offline viewing and analysis
    Use the streamtool getjobtopology command to capture job topology information that you can view and analyze offline.
  - Enabling resource load protection for Teracloud® Streams instances
    The resource load protection option controls whether overload protection is enabled as determined by the values of three metrics: CPU utilization, memory utilization, and network bandwidth utilization. When you enable resource load protection, Streams prevents additional work (new PEs) from being placed on an overloaded resource.
  - Changing resource usage thresholds
    Each resource has a fixed capacity, for example CPU cores. If PEs are placed on a resource that needs more CPU processing power than what is available, the resource becomes overloaded and will have poor performance. You can use resource usage thresholds to identify PE load balancing recommendations or, together with the resourceLoadProtectionEnabled instance property, to directly protect resources from being overloaded.
  - Disabling resource load protection for Teracloud® Streams
    You can disable resource load protection for the instance or you can override resource load protection for individual job submissions.
  - Viewing Teracloud® Streams name service references for jobs
    Use the streamtool getnsentry command to query the name service of a Teracloud® Streams instance.
- Recovery
  You can back up your Teracloud® Streams system files and directories and then restore them later if necessary. In general, you can recover from application and runtime failures without restoring Teracloud Streams from a backup.
- Streams Console
  You can use the Streams Console to monitor and manage the Teracloud® Streams instances and applications in your domain from any computer that has HTTP connectivity to the server that is running the web management service.
- Logs and traces
  Teracloud® Streams provides options that enable administrators, instance owners, and application developers to manage log and trace data.
- Managing and monitoring Teracloud® Streams using management APIs
  Teracloud® Streams provides two API sets to manage and monitor Streams services and jobs.
Developing
Develop stream applications with the Streams Processing Language (SPL), Java, and Python.
Troubleshooting
Resolve problems with Teracloud® Streams using the troubleshooting tools provided with the product as well as the resources offered by Teracloud Support.
Reference
Find details on the SPL language, toolkits, APIs, commands, and more.
Glossary
Use this glossary to find terms and definitions for Teracloud® Streams.

Enabling resource load protection for Teracloud® Streams instances

The resource load protection option controls whether overload protection is enabled as determined by the values of three metrics: CPU utilization, memory utilization, and network bandwidth utilization. When you enable resource load protection, Streams prevents additional work (new PEs) from being placed on an overloaded resource.

After you enable resource load protection, you can set overload threshold values for each metric. You set threshold values by modifying the properties that correspond to the metrics. A resource is considered overloaded if any of the values of the three metrics is overloaded. If all the candidate resources for any PE within a job are overloaded, the job submission fails.

About this task

Procedure

Specify the resourceLoadProtectionEnabled instance property when you create or update an instance:
```
streamtool setproperty instance.resourceLoadProtectionEnabled=true
```
Customize the overload protection for your circumstances by setting threshold values.
- Example 1:
  
  Suppose that you expect that some PEs will have normal CPU usage, greater memory usage, but negligible network usage. You can set the upper thresholds to the following values:
```
streamtool setproperty instance.resourceCpuUsageUpperThreshold=75
```
```
instance.resourceMemoryUsageUpperThreshold=50 
instance.resourceNetworkBandwidthUsageUpperThreshold=100
```
  Note: The default value for the upper and lower thresholds is 100.
  An upper threshold value of 100 skips the protection for that metric's overload.
  The upper and lower thresholds for each metric work together. If you change an upper threshold for a metric to 75 without changing its lower threshold to less than or equal to 75, you will get an error.
- Example 2:
  Suppose that you expect that memory utilization for a PE will require 30% of the resource's utilization You want the resource protection for memory usage invoked sooner. This is a more conservative approach. You can set the lower threshold to the following value:
```
streamtool setproperty instance.resourceMemoryUsageLowerThreshold=60 
```
  The lower threshold setting of 60% protects the memory usage better than a setting of 80%.