Dstream from the source codeAs can be seen from here, Dstream is the core of spark streaming, the core of Spark core is the RDD, it also has dependency and compute. More critical is the following code:This is a hashmap, with time as key, with the RDD as value, which is also proof of the constant generation of rdd over time, generating dependency jobs, and running through Jobscheduler on the cluster. Again, Dstream is the template for the RDD.Dstream
stage 483.0 (TID 3 4 ms on localhost (executor driver) (1/1) 2018-10-22 11:28:16 INFO taskschedulerimpl:54-removed TaskSet 483.0, whose tasks all completed, from pool20 18-10-22 11:28:16 INFO dagscheduler:54-resultstage 483 (print at directkafka.scala:47) finished in 0.008 s2018-10- 11:28:16 INFO dagscheduler:54-job 241 Finished:print at Directkafka.scala:47, took 0.009993 s----------------- --------------------------time:1540178896000 Ms-------------------------------------------Start producer
loop requests
The operation that triggers network requests keeps wireless signals for a period of time. We can package scattered network requests for one operation to avoid excessive power consumption caused by wireless signals.
Is what JobScheduler API does. It combines the desired wake-up time based on the current situation and task, for example, when the instance is being charged or connected to WiFi, or when the task is executed together. We ca
Jobscheduler API does. It combines the ideal wake-up time based on current situations and tasks, such as when charging or connecting to WiFi, or concentrating on tasks. We can use this API to implement a lot of free scheduling algorithms.
3) Electric Power optimization strategy
• Check all wake-up locks for redundancy or unwanted locations.
• Centralize relevant data requests and send them uniformly; Streamline data and reduce the transfer of unwa
time intervals, generate different RDD graph instances.Starting with the spark streaming itself:1. Generate template for Rdd dag: DStream Graph2 requires a timeline-based job Controller3 requires inputstreamings and outputstreamings, representing the input and output of the data4 The specific job runs on the spark cluster, and because streaming is critical to the system's fault tolerance regardless of whether the cluster is digestible5 transaction processing, we hope that the data flowing in wi
, which is composed of a continuous rdd on a group time series, containing a structure that has the duration as a key and an rdd as value. Each RDD contains a data stream at a specific time interval that can be persisted through persist. After accepting the constant flow of data, a queue is maintained in the Blockgenerator, the stream data is placed in the queue, and all of its data is merged into an RDD (data in this interval) after the processing interval arrives. Its job submission is similar
Jobscheduler, where theReceivertracker is R .Eceivertracker object, take a look at the implementation of this method:You can see that the final call to the ReceivedblocktrackerAllocatedblocktobatch Method:Here first according to Streamid, fromThe received block queue is taken out of the streamidtounallocatedblockqueues, and the Streamid and block queues are encapsulated as allocatedblocks, and finally according to the batchtime the corresponding allo
What changes have been made to Android NFirst, performance improvement
Doze Super Power Save mode
Mobile phone in off at the same time there is no charging situation, will enter the NAP state, the app location service, access network, CPU background-running and other background services will be stopped, do not allow scheduled tasks, ignore wake locks, stop WiFi scanner.Will affect the app's keepalive, especially for apps that need to receive message classes. Google recommends using
broadcasts. For example, JobScheduler The API provides a robust mechanism to schedule network operations that meet specified conditions, such as connecting to an infinite traffic network. You can even use it JobScheduler to adapt to changes in the content provider.For more information about background optimizations in Android N and how to overwrite apps, see background optimizations.Permission changes
JobSchedule is added after Android5.0, the previous version did not.The JobSchedule principle is a programmatic mechanism that arranges tasks in an appropriate and practical way. The optional timing is provided, as follows:1 is performed under Available networks. Before 7.0, applications could perform tasks by listening to network changes, but only if the application had to survive. After 7.0, such APIs have been invalidated, but the jobschedule mechanism provides monitoring of network changes.
not supported;For these two main target SDK for Android Oreo will be affected, but unfortunately users can now enable this restriction on the app.3. Background apps get more restrictive restrictions to get the location. All applications running on Android Oreo will be affected and need to be addressed immediately.1. ServiceThe most important principle is that the user is visible. If the application is doing resource-intensive work, the user should be aware that starting the service from the bac
): Complete the process of Service1 in the projectusingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Diagnostics;usingSystem.Linq;usingsystem.serviceprocess;usingSystem.Text;usingSystem.Threading.Tasks;namespacequartztimerwinserapp{ Public Partial classservice1:servicebase {Jobscheduler Scheduler; PublicService1 () {InitializeComponent (); } protected Override voidOnStart (string[] args) {Schedu
AlarmManager.setAndAllowWhileIdle().
WiFi scans is not performed.
Syncs and jobs for your sync adapters and is not JobScheduler permitted to run.
3. APP StandbyWith this preview, the system could determine that apps is idle when they is not in active use. 4, adoptable Storage DevicesWith this preview, users can adopt External storage devices such as SD cards. Adopting an external storage device encrypts and formats the device to behave
the heart of spark streaming , and the core of Spark Core is RDD, it also has dependency and compute. More critical is the following code:This is a HashMap, with time as key, with the RDD as value, which is also proof of the passage of time , constantly generate RDD, generate dependency jobs, and run through Jobscheduler on the cluster. Again, DStream is The template for the RDD. DStreamcan be said to be a logical level,RDDis the physical leve
will only calculate the failed shards;Fault tolerance for 5.Checkpoint and persist6. Data scheduling resiliency, independent of DAG, Jobscheduler, etc.7. The high elasticity of data Shard, can set the number of shards manually, set the Shard function: repartition default to Shuffle mechanism, you can choose Coalesce function for sharding settingAn RDD is a collection of data shards distributed across a cluster, with the same computational logic for e
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