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Top results related to what is azure event hub partition recovery
Top Answer
Answered Jan 04, 2015 · 9 votes
A fields gateway is simply an aggregation point for a range of in-place sensors. Many low powered / basic devices do not have enough capacity to run secured HTTP sessions so in these cases there will typically be a gateway to which these devices send their data. The gateway can aggregate / store and then forward the data securely onto Azure Event Hubs.
To answer your question: it isn't a device-side SDK.
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Top Answer
Answered Jan 27, 2019 · 17 votes
From the docs:
Consumer groups: A view (state, position, or offset) of an entire event hub. Consumer groups enable consuming applications to each have a separate view of the event stream. They read the stream independently at their own pace and with their own offsets.
Diagram:
According to this consumer groups are the way to logically separate your consumers, so they only see the events they are interested in.
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Top Answer
Answered Jul 12, 2023 · 2 votes
In short, yes. In one specific scenario, it is possible to see two instances process the same partition for a batch or two. The linked thread discussing parallel execution with single-dispatch is incorrect.
Partitions and ownership
Generally speaking, every partition can have only one active reader. However, it is possible to have two Function instances dispatching events for the same partition for a small period of overlap (1-2 batches) when instances are scaling and partition ownership rebalances.
If the old owner is holding events in memory and dispatches them, it may not be aware that the partition has a new owner. The old owner becomes aware of the change the next time that it attempts to read or when the trigger's load balancing loop ticks (30 seconds by default). At this point, the old owner is no longer permitted to read from the partition and will stop dispatching events after your code completes processing the current event/batch.
Outside of that scenario, there will not be parallel processing for any partition. Whether using single-dispatch or multi-dispatch, each time your Function is invoked to perform processing, the trigger will wait for that invocation to complete (and checkpoint, if needed) before dispatching another event from that partition.
Ordering and duplication
With respect to ordering, the general guarantee is that the trigger will dispatch each event in the order that it appears in the partition. However, you may see rewinds where the trigger repositions to an earlier point in time and replays events. This happens when scaling occurs and ownership rebalances, a host machine crashes or migrates, or when there's an exception in the runtime that causes the trigger to be restarted.
That will cause the trigger to position its reader at the last checkpoint written and to start dispatching from there. The events will be read in order from that point forward. To your application, though, ordering will be disrupted and it will see events that it already processed.
In short, its important that your application keep the Event Hubs "at least once" guarantee in mind and ensure that processing is idempotent and can handle rewinds.
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Top Answer
Answered May 09, 2019 · 62 votes
TLDR: This behavior is absolutely normal.
Why can't Lease Management be smooth & exception-free: To give more control on the situation to developer.
The really long story - all-the-way from Basics EventProcessorhost (hereby EPH - is very similar to what __consumer_offset topic does for Kafka Consumers - partition ownership & checkpoint store) is written by Microsoft Azure EventHubs team themselves - to translate all of the EventHubs partition receiver Gu into a simple onReceive(Events) callback.
EPH is used to address 2 general, major, well-known problems while reading out of a high-throughput partitioned streams like EventHubs:
- fault tolerant receive pipe-line - for ex: a simpler version of the problem - if the host running a PartitionReceiver dies and comes back - it needs to resume processing from where it left. To remember the last successfully processed EventData , EPH uses the blob supplied to EPH constructor to store the checkpoints - when ever user invokes context.CheckpointAsync() . Eventually, when the host process dies (for ex: abruptly reboots or hits a hardware fault and never/comesback) - any EPH instance can pick up this task and resume from that Checkpoint .
- Balance/distribute partitions across EPH instances - lets say, if there are 10 partitions and 2 EPH instances processing events from these 10 partitions - we need a way to divide partitions across the instances ( PartitionManager component of EPH library does this). We use Azure Storage - Blob LeaseManagement-feature to implement this. As of version 2.2.10 - to simplify the problem, EPH assumes that all partitions are loaded equally.
With this, lets try to see what's going on: So, to start with, in the above example of 10 event hub partitions and 2 EPH instances processing events out of them:
- lets say the first EPH instance - EPH1 started, at-first, alone and a part of start-up, it created receivers to all 10 partitions and is processing events. In the start up - EPH1 will announce that it owns all these 10 partitions by acquiring Leases on 10 storage blobs representing these 10 event hub partitions (with a standard nomenclature- which EPH internally creates in the Storage account - from the StorageConnectionString passed to the ctor). Leases will be acquired for a set time, after which the EPH instance will loose the ownership on this Partition.
- EPH1 continually announces once in a while - that it is still owning those partitions - by renewing leases on the blob. Frequency of renewal, along with other useful tuning, can be performed using PartitionManagerOptions
- now, lets say, EPH2 starts up - and you supplied the same AzureStorageAccount as EPH1 to the ctor of EPH2 as well. Right now, it has 0 partitions to process. So, to achieve balance of partitions across EPH instances, it will go ahead and download the list of all leaseblobs which has the mapping of owner to partitionId. From this, it will STEAL leases for its fair share of partitions - which is 5 in our example, and will announce that information on that lease blob. As part of this, EPH2 reads the latest checkpoint written by PartitionX it wants to steal the lease for and goes ahead and creates corresponding PartitionReceiver's with the EPOCH same as the one in the Checkpoint.
- As a result, EPH1 will loose ownership of these 5 partitions and will run into different errors based on the exact state it is in. if EPH1 is actually invoking the PartitionReceiver.Receive() call - while EPH2 is creating the PartitionReceiver on the same receiver - EPH1 will experience ReceiverDisconnectedException. This will eventually, invoke IEventProcessor.Close(CloseReason=LeaseLost). Note that, probability of hitting this specific Exception is higher, if the messages being received are larger or the PrefetchCount is smaller - as in both cases the receiver would be performing more aggressive I/O.
- if EPH1 is in the state of checkpointing the lease or renewing the lease, while the EPH2 stole the lease, the EventProcessorOptions.ExceptionReceived eventHandler would be signaled with a leaselostException (with 409 conflict error on the leaseblob) - which also eventually invokes IEventProcess.Close(LeaseLost).
Why can't Lease Management be smooth & exception-free:
To keep the consumer simple and error-free, lease management related exceptions could have been swallowed by EPH and not notified to the user-code at all. However, we realized, throwing LeaseLostException could empower customers to find interesting bugs in IEventProcessor.ProcessEvents() callback - for which the symptom would be - frequent partition-moves
- minor network outage on a specific machine - due to which EPH1 fails to renew leases and comes back up! - and imagine if the n/w of this machine stands flaky for a day - EPH instances are going to play ping-pong with Partitions! This machine will continuously try to steal the lease from other machine - which is legitimate from EPH point-of-view - but, is a total disaster for the user of EPH - as it completely interferes with the processing pipe. EPH - would exactly see a ReceiverDisconnectedException, when the n/w comes back up on this flaky m/c! We think the best and infact the only way is to enable the developer to smell this!
- or a simple scenario like, having a bug in ProcessEvents logic - which throws unhandled exceptions which are fatal and brings down the whole process - ex: a poison event. This partition is going to move around a lot.
- customers, performing write/delete operations on the same storage account which EPH is also using - by mistake (like an automated clean-up script) etc.
- last but not the least - which we never wish could happen - say a 5 min outage on Azure d.c where a specific EventHub.Partition is located - say n/w incident. Partitions are going to move around across EPH instances.
Basically, in majority of situations, it would be tricky - for us to detect the diff. between these situations and a legitimate leaseLost due to balancing and we want to delegate control of these situations to the Developer.
more on Event Hubs...
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Top Answer
Answered Jun 03, 2019 · 16 votes
This page offers a good overview about the different IoT options on Azure: https://learn.microsoft.com/en-us/azure/iot-central/overview-iot-options
Microsoft Azure IoT Central and Azure IoT offer several options for building an IoT solution. These options are appropriate for different sets of customer requirements:
Azure IoT Central is a software as a service (SaaS) solution that uses a model-based approach to help you to build enterprise-grade IoT solutions without requiring expertise in cloud-solution development.
Azure IoT solution accelerators are an enterprise-grade collection of solution accelerators built on Azure platform as a service (PaaS) that help you accelerate the development of custom IoT solutions.
All of those build on IoT Hub which is the foundational PaaS (Plattform as a Service) offering for device connectivity, management and communication.
Other Answers
Answered Apr 13, 2020 · 27 votes
Differences between the two IoT offerings by Azure:
Other Answers
Answered Jun 23, 2020 · 13 votes
Here is a table view on major differences between IOT central and IOT hub
╔══════════════════════════════╦════════════════════════════════╗║ Azure IOT Central ║ Azure IOT Hub ║╠══════════════════════════════╬════════════════════════════════╣║ A SaaS solution that makes ║ Managed service, acts as a ║║ it easy to get started and ║ central message hub for ║║ pull new data into your ║ bi-directional communication ║║ existing business processes. ║ between IOT app and the device ║╠══════════════════════════════╬════════════════════════════════╣║ Provide App template for ║ Anyone can use IOT hub to ║║ Priority Industry Verticals ║ build IOT solutions with ║║ ║ reliable and secure ║║ ║ communications between ║║ ║ millions of IOT devices ║╠══════════════════════════════╬════════════════════════════════╣║ Provides Seamless device ║ Supports Multi-language and ║║ connectivity and management ║ open source SDKs ║╠══════════════════════════════╬════════════════════════════════╣║ Connect millions ║ Provision devices at scale ║║ of devices and manage ║ with IOT device provisioning ║║ ingress/egress of data ║ service ║╚══════════════════════════════╩════════════════════════════════╝-
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learn.microsoft.com › en-us › azurePartitioning in Event Hubs and Kafka - Azure Architecture Center
learn.microsoft.com › en-us › azureLearn about partitioning in Kafka and Event Hubs with Kafka, see how many partitions to use in ingestion pipelines, and also see how to assign events to partitions.
stackoverflow.com › questions › 59086482Understanding Azure Event Hubs partitioned consumer pattern
stackoverflow.com › questions › 59086482Nov 28, 2019 · Azure Event Hub uses the partitioned consumer pattern described in the docs . I have some problems understanding the consumer side of this model when it comes to a real world scenario. So lets say I have 1000 messages send to the event hub with 4 partitions, not defining any partition Id.
People also ask
What is Azure Event Hub partition?
- An Azure Event hub partition is an ordered sequence of events. It acts like a queue, when the newer events arrive, they are added to the end of the partition. Data is retained for a fixed amount of time in Azure event hub partitions. The retention time can be configured by the user and is applicable to all the partitions in the event hub.
Azure Event Hubs Partitions – Azure Data Engineering
azurede.com/2020/06/01/event-hubs-partitions/Does Azure Event Hub use a partitioned consumer pattern?
- Azure Event Hub uses the partitioned consumer pattern described in the docs . I have some problems understanding the consumer side of this model when it comes to a real world scenario. So lets say I have 1000 messages send to the event hub with 4 partitions, not defining any partition Id.
Understanding Azure Event Hubs partitioned consumer pattern
stackoverflow.com/questions/59086482/understanding-azure-event-hubs-partitioned-consumer-patternWhat is a partition in event hub?
- A partition is an ordered sequence of events that is held in an event hub. As newer events arrive, they're added to the end of this sequence. For more information about partitions in general, see Partitions You can specify the number of partitions at the time of creating an event hub.
Dynamically add partitions to an event hub in Azure Event Hubs - Azure
learn.microsoft.com/en-us/azure/event-hubs/dynamically-add-partitionsHow does Azure Event Hub billing work?
- Azure event hubs billing is independent of the number of partitions that users choose to create. Microsoft recommends that the decision on the number of partitions should include both, the future scalability and the downstream parallelism (concurrent access) required. Loading...
Azure Event Hubs Partitions – Azure Data Engineering
azurede.com/2020/06/01/event-hubs-partitions/www.linkedin.com › pulse › azure-event-hubAzure Event Hub – Understanding & Designing of Partitions and ...
www.linkedin.com › pulse › azure-event-hubJan 7, 2020 · Figure 1. Architecture - Event Hub. Event Hubs contains the following key components: • Event producers: Any entity that sends data to an event hub. Event publishers can publish events using...
techcommunity.microsoft.com › t5 › azure-paas-blogHow to verify if Azure Event Hub partition is working by ...
techcommunity.microsoft.com › t5 › azure-paas-blogDec 13, 2021 · Published Dec 13 2021 09:33 PM 5,119 Views. undefined. In some circumstances, we may wonder if the partitions in our Azure Event Hub are working as expected from both of Send and Receive sides. This article provides some troubleshooting threads based on Azure Service Bus Explorer tool mainly to narrow down the status of Azure Event Hub partition.
azurede.com › 2020/06/01 › event-hubs-partitionsAzure Event Hubs Partitions - Azure Data Engineering
azurede.com › 2020/06/01 › event-hubs-partitionsJun 1, 2020 · An Azure Event hub partition is an ordered sequence of events. It acts like a queue, when the newer events arrive, they are added to the end of the partition. Data is retained for a fixed amount of time in Azure event hub partitions. The retention time can be configured by the user and is…
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