There are ways to get both the number of executors and the number of cores in a cluster from Spark. Here is a bit of Scala utility code that I’ve used in the past. You should easily be able to adapt it to Java. There are two key ideas: The number of workers is the … Read more
You need add the following to your build.gradle file: repositories { mavenCentral() maven { url “http://dl.bintray.com/journeyapps/maven” } } dependencies { // Supports Android 4.0.3 and later (API level 15) compile ‘com.journeyapps:zxing-android-embedded:2.0.1@aar’ // Supports Android 2.1 and later (API level 7), but not optimal for later Android versions. // If you only plan on supporting Android … Read more
You can either use WMI or the System.Diagnostics namespace. From there you can grab any of the performance counters you wish (however it takes a second (1-1.5s) to initialize those – reading values is ok, only initialization is slow) Code can look then like this: using System.Diagnostics; public static Double Calculate(CounterSample oldSample, CounterSample newSample) { … Read more
grep -c ^processor /proc/cpuinfo will count the number of lines starting with “processor” in /proc/cpuinfo For systems with hyper-threading, you can use grep ^cpu\\scores /proc/cpuinfo | uniq | awk ‘{print $4}’ which should return (for example) 8 (whereas the command above would return 16)
To run Tensorflow on one single CPU thread, I use: session_conf = tf.ConfigProto( intra_op_parallelism_threads=1, inter_op_parallelism_threads=1) sess = tf.Session(config=session_conf) device_count limits the number of CPUs being used, not the number of cores or threads. tensorflow/tensorflow/core/protobuf/config.proto says: message ConfigProto { // Map from device type name (e.g., “CPU” or “GPU” ) to maximum // number of devices … Read more
A core is usually the basic computation unit of the CPU – it can run a single program context (or multiple ones if it supports hardware threads such as hyperthreading on Intel CPUs), maintaining the correct program state, registers, and correct execution order, and performing the operations through ALUs. For optimization purposes, a core can … Read more
Time Server Set up a time server on your local network. Have your app contact that local time server to query the current time. Consider placing that time server computer in network’s DMZ so as to updates from time servers on the Internet such as the pool.ntp.org project or those provided by the United States … Read more
Synchronized HashMap： Each method is synchronized using an object level lock. So the get and put methods on synchMap acquire a lock. Locking the entire collection is a performance overhead. While one thread holds on to the lock, no other thread can use the collection. ConcurrentHashMap was introduced in JDK 5. There is no locking … Read more
First step: Put your image in a defined location in your JAR-file. If you put it into the src-folder, maybe your IDE or your build-tool will package it to the JAR automatically. Otherwise check the documentation of your IDE/build-tool, in which location you have to put it. Second step: Access the file from your program. … Read more
In addition to what was already said, String literals [ie, Strings like “abcd” but not like new String(“abcd”)] in Java are interned – this means that every time you refer to “abcd”, you get a reference to a single String instance, rather than a new one each time. So you will have: String a = … Read more