I created a Preemptive instance to test out the GCP. I can't find a way to turn Preemptive off and basically migrate the instance to a normal one.
Can I turn Preemptive off or do I need to create a brand new instance...and loose some of my testing work?
Related
I am building a system that will consist of several instances, each running our Optaplanner implementation. These instances will monitor a common queue for incoming jobs. I don't want an instance that is already busy to take the job, so I want to check the number of ongoing jobs in the solver manager.
In the debugger, it looks like the solverManager has some stuff that could help me check that (problemIdToSolverJobMap.size() < parallelSolverCount would work for instance), but these are private ant not accesible to me.
How do I in the most robust way check the status of the solver manager as a whole, not for a specific job?
That would be useful indeed. This is an API gap, clearly. Please create a jira.
We are developing a Web API using .Net Core. To perform background tasks we have used Hosted Services.
System has been hosted in AWS Beantalk Environment with the Load Balancer. So based on the load Beanstalk creates/remove new instances of the system.
Our problem is,
Since background services also runs inside the API, When load balancer increases the instances, number of background services also get increased and there is a possibility to execute same task multiple times. Ideally there should be only one instance of background services.
One way to tackle this is to stop executing background services when in a load balanced environment and have a dedicated non-load balanced single instance environment for background services only.
That is a bit ugly solution. So,
1) Is there a better solution for this?
2) Is there a way to identify the primary instance while in a load balanced environment? If so I can conditionally register Hosted services.
Any help is really appreciated.
Thanks
I am facing the same scenario and thinking of a way to implement a custom service architecture that can run normally on all of the instance but to take advantage of pub/sub broker and distributed memory service so those small services will contact each other and coordinate what's to be done. It's complicated to develop yes but a very robust solution IMO.
You'll "have to" use a distributed "lock" system. You'll have to use, for example, a distributed memory cache who put a lock when someone (a node of your cluster) is working on background. If another node is trying to do the same job, he'll be locked by the first lock if the work isn't done yet.
What i mean, if all your nodes doesn't have a "sync handler" you can't handle this kind of situation. It could be SQL app lock, distributed memory cache or other things ..
There is something called Mutex but even that won't control this in multi-instance environment. However, there are ways to control it to some level (may be even 100%). One way would be to keep a tracker in the database. e.g. if the job has to run daily, before starting your job in the background service you might wanna query the database if there is any entry for today, if not then you will insert an entry and start your job.
Is it possible to notify an application running on a Google Compute VM when the VM migrates to different hardware?
I'm a developer for an application (HMMER) that makes heavy use of vector instructions (SSE/AVX/AVX-512). The version I'm working on probes its hardware at startup to determine which vector instructions are available and picks the best set.
We've been looking at running our program on Google Compute and other cloud engines, and one concern is that, if a VM migrates from one physical machine to another while running our program, the new machine might support different instructions, causing our program to either crash or execute more slowly than it could.
Is there a way to notify applications running on a Google Compute VM when the VM migrates? The only relevant information I've found is that you can set a VM to perform a shutdown/reboot sequence when it migrates, which would kill any currently-executing programs but would at least let the user know that they needed to restart the program.
We ensure that your VM instances never live migrate between physical machines in a way that would cause your programs to crash the way you describe.
However, for your use case you probably want to specify a minimum CPU platform version. You can use this to ensure that e.g. your instance has the new Skylake AVX instructions available. See the documentation on Specifying the Minimum CPU Platform for further details.
As per the Live Migration docs:
Live migration does not change any attributes or properties of the VM
itself. The live migration process just transfers a running VM from
one host machine to another. All VM properties and attributes remain
unchanged, including things like internal and external IP addresses,
instance metadata, block storage data and volumes, OS and application
state, network settings, network connections, and so on.
Google does provide few controls to set the instance availability policies which also lets you control aspects of live migration. Here they also mention what you can look for to determine when live migration has taken place.
Live migrate
By default, standard instances are set to live migrate, where Google
Compute Engine automatically migrates your instance away from an
infrastructure maintenance event, and your instance remains running
during the migration. Your instance might experience a short period of
decreased performance, although generally most instances should not
notice any difference. This is ideal for instances that require
constant uptime, and can tolerate a short period of decreased
performance.
When Google Compute Engine migrates your instance, it reports a system
event that is published to the list of zone operations. You can review
this event by performing a gcloud compute operations list --zones ZONE
request or by viewing the list of operations in the Google Cloud
Platform Console, or through an API request. The event will appear
with the following text:
compute.instances.migrateOnHostMaintenance
In addition, you can detect directly on the VM when a maintenance event is about to happen.
Getting Live Migration Notices
The metadata server provides information about an instance's
scheduling options and settings, through the scheduling/
directory and the maintenance-event attribute. You can use these
attributes to learn about a virtual machine instance's scheduling
options, and use this metadata to notify you when a maintenance event
is about to happen through the maintenance-event attribute. By
default, all virtual machine instances are set to live migrate so the
metadata server will receive maintenance event notices before a VM
instance is live migrated. If you opted to have your VM instance
terminated during maintenance, then Compute Engine will automatically
terminate and optionally restart your VM instance if the
automaticRestart attribute is set. To learn more about maintenance
events and instance behavior during the events, read about scheduling
options and settings.
You can learn when a maintenance event will happen by querying the
maintenance-event attribute periodically. The value of this
attribute will change 60 seconds before a maintenance event starts,
giving your application code a way to trigger any tasks you want to
perform prior to a maintenance event, such as backing up data or
updating logs. Compute Engine also offers a sample Python script
to demonstrate how to check for maintenance event notices.
You can use the maintenance-event attribute with the waiting for
updates feature to notify your scripts and applications when a
maintenance event is about to start and end. This lets you automate
any actions that you might want to run before or after the event. The
following Python sample provides an example of how you might implement
these two features together.
You can also choose to terminate and optionally restart your instance.
Terminate and (optionally) restart
If you do not want your instance to live migrate, you can choose to
terminate and optionally restart your instance. With this option,
Google Compute Engine will signal your instance to shut down, wait for
a short period of time for your instance to shut down cleanly,
terminate the instance, and restart it away from the maintenance
event. This option is ideal for instances that demand constant,
maximum performance, and your overall application is built to handle
instance failures or reboots.
Look at the Setting availability policies section for more details on how to configure this.
If you use an instance with a GPU or a preemptible instance be aware that live migration is not supported:
Live migration and GPUs
Instances with GPUs attached cannot be live migrated. They must be set
to terminate and optionally restart. Compute Engine offers a 60 minute
notice before a VM instance with a GPU attached is terminated. To
learn more about these maintenance event notices, read Getting live
migration notices.
To learn more about handling host maintenance with GPUs, read
Handling host maintenance on the GPUs documentation.
Live migration for preemptible instances
You cannot configure a preemptible instances to live migrate. The
maintenance behavior for preemptible instances is always set to
TERMINATE by default, and you cannot change this option. It is also
not possible to set the automatic restart option for preemptible
instances.
As Ramesh mentioned, you can specify the minimum CPU platform to ensure you are only migrated to an instance which has at least the minimum CPU platform you specified. At a high level it looks like:
In summary, when you specify a minimum CPU platform:
Compute Engine always uses the minimum CPU platform where available.
If the minimum CPU platform is not available or the minimum CPU platform is older than the zone default, and a newer CPU platform is
available for the same price, Compute Engine uses the newer platform.
If the minimum CPU platform is not available in the specified zone and there are no newer platforms available without extra cost, the
server returns a 400 error indicating that the CPU is unavailable.
I have a cloudbees enterprise instance that I use for performance and automated UI testing.
The free instance (which is limited in memory) cannot support the memory or request per second that we have for testing.
I would like to have the instance automatically hibernated when I am not using it but have it wake up when requests come in. I would configure a jenkins job to wake the app up (by issuing a request) before kicking off my sauce lab based selenium jobs.
My question is how do I configure automatic hibernation? The control panel has minimum of one instance which I guess means that the one instance stays up.
You are right - currently automatic hibernation is only for free applications. When an application is hibernated (vs stopped) then it will be automatically woken whenever someone needs to access it.
What you could do for this is to have a job set your application to hibernated, say once a day, (or at certain time of the day when you know it won't be needed). When it is needed again - you won't need to do anything - simply accessing it will cause it to be activated (woken) again - so your test script can just insure that is the case (and ideally, after a test run, set it to hibernated again).
It really depends how often the app is needed - if you can work out what points it isn't needed and trigger the hibernate off that (eg after a test run) then that is ideal (you minimise cost).
I am new to weblogic server. I am using work manager. I want to know what is work manager and why we need it. What is the difference between normal request with out work manager and with work manager !!
I think the documentation is rather good on this subject.
WebLogic Server prioritizes work and allocates threads based on an
execution model that takes into
account administrator-defined
parameters and actual run-time
performance and throughput.
Administrators can configure a set of
scheduling guidelines and associate
them with one or more applications, or
with particular application
components. For example, you can
associate one set of scheduling
guidelines for one application, and
another set of guidelines for other
application. At run-time, WebLogic
Server uses these guidelines to assign
pending work and enqueued requests to
execution threads.
Essentially, with work managers you can attach a scheduling policy to an application to e.g. make sure that a specific application gets a fair share of the available computing resources under a heavy load situation. Or you might want to restict the maximum number of threads that will be allocated to an application to prevent a buggy/untested application to bring the whole application server to its knees. (But surely all apps have been tested not to do anything like that.... ;) )
Outside of modifying the default allocation algorithms, the Work Manager is also useful if you are using a Foreign JMS Provider (such as IBM MQ) and need to process more than 16 messages at a time.