Cloud based distributed TLC
1 Motivation
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Move long running model checking off local machine into the cloud (Short running models not ideal because instance spin-up time is approximately five minutes)
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Maximize cloud instance resource utilization by providing fine-tuned TLC parameter pre-sets optimized for the given cloud instance type
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Minimizes costs by terminating cloud instances immediately after TLC model checking has ended
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Unless email delivery of model checking result fails (n this case the machine remains running for the user to pick up the result manually)
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User then has to terminate the instance manually!
2 Warning
Using cloud based TLC launches compute instances at your cloud provider which may incur costs. While the cloud based distributed TLC tries to minimize costs by terminating instances as soon as possible, do not rely on it. Always check if cloud instances have been correctly terminated.
3 Limitation
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Only supports a single cloud provider (Amazon EC2) as of now
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Runs TLC in non-distributed mode on a single cloud instance only as of now
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Only a single instance type (m4.2xlarge) supported as of now
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Cloud based distributed TLC cannot recover from a checkpoint
4 Usage
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Set AWS access key and secret as environment variables prior to launching the Toolbox. See the example with dummy keys below.
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export AWS_ACCESS_KEY_ID=AKIA7D89HCLJKHZASD7F
export AWS_SECRET_ACCESS_KEY=6FDASAIG7DAS976TYDKHCGQAS5D\FA77
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Create a specification and a model
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Open your model in the model editor
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Expand the “How to run” section of the “Model Overview” page
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Select “aws-ec2” from the “Run in distributed mode” drop down
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Enter an email address into “Result mailto address” at which you want to receive the model checking result
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Click “Run TLC” to start model checking in the cloud and wait for the start-up to finish (it takes approximately five minutes to set-up the cloud instance)
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The Toolbox switches to the “Model checking results” page and opens a progress dialog indicating the state of cloud instance provisioning
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After provisioning the cloud instance, the Toolbox prompts the user to open a website in a browser.
This website is hosted on the cloud instance and shows the TLC process output as well as runtime statistics similar to Toolbox stats
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Walk out and enjoy the weekend while TLC is busy checking
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On Monday expect to find an email in your inbox
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Save MC.out file somewhere to disc
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Switch back to the Toolbox and open the model editor
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Open the “Model Checking Results” page
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Import the MC.out from disc
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Voilá
5 Common problems
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The Toolbox fails to start the cloud instance
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Re-check your credentials
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If your credentials are correct, please turn on debug logging (start the Toolbox executable with “toolbox -console -consolelog”) and send us the output. You might have encountered a bug in cloud based distributed TLC.
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The runtime statistics (web browser) indicate that TLC has finished model checking, but no result is sent via email.
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Check your email spam folder if the model checking result has incorrectly been classified as spam
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Another reason why mail delivery might fail, are too strict spam counter measures at the mail server level. You might want to try to use a different email address (domain part) in the future.
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Copy & paste the MC.out content from the browser window into a plain text file and load it from there (see 4↑)