Sep 10, 2020 getOrElseUpdate(BlockManager.scala:881) at org.apache.spark.rdd.RDD. MapPartitionsRDD.compute(MapPartitionsRDD.scala:52) at 

May 27, 2020 Using maps in scala is very simple. getOrElseUpdate("yoleen1",op(5,6))//If the key does not exist, return the default value and add it to the 

Cause. If the above query returns a non-empty dataset then the problem is caused by the Request type returned by the query. Resolution. Remove these request types or add at least one field to the request type. Play Framework - The High Velocity Web Framework For Java and Scala.

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.getOrElseUpdate makes it convenient to use a mutable Map as a cache: the second parameter to .getOrElseUpdate is a lazy "by-name" parameter, and is only evaluated when the key is not found in the Map. This provides the common "check if key present, if so return value, otherwise insert new value and return that" workflow built in. As discussed above, the getOrElseUpdate () method retrieves the specified tweets from the cache if they exist, otherwise, it calls our wrapper for the Twitter API to retrieve the latest values. This is a very common usage pattern for any cache. This one API call will probably suffice for the great majority of applications. 4.3.

Benchmarks for groupBy / map getOrElseUpdate slowdown - GroupByBench.scala. Skip to content.

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This is the documentation for the Scala standard library. Package structure . The scala package contains core types like Int, Float, Array or Option which are accessible in all Scala compilation units without explicit qualification or imports. As I understand, TrieMap.getOrElseUpdate is still not truly atomic, and this fixes only returned result (it could return different instances for different callers before this fix), so the updater function still might be called several times, as documentation (for 2.11.7) says: Note: This method will invoke op at most once.

Jul 23, 2013 Updating a Map in Scala. Relevant references: But how can we increase the count if the word is already in the map? Using Only Built-in Methods.

Valentin Nikotin.

Map [ String, String ] () map.getOrElseUpdate ( "key", { map.getOrElseUpdate ( "key", "value1" ) "value2" }) map. Note: getOrElseUpdate is not an atomic operation in EhCache and is implemented as a get followed by computing the value, then a set. This means it’s possible for the value to be computed multiple times if multiple threads are calling getOrElse simultaneously. * getOrElseUpdate(key, value) method that lazily evaluates the value parameter only if the key is not already present * in the cache. * * You may be asking, why not just use Scala's ConcurrentMap interface, which already has a getOrElseUpdate method? * * val cache = new ConcurrentHashMap().asScala * cache.getOrElseUpdate("foo", "bar") // BAD idea * package com.yahoo.maha import java.sql.ResultSet package object jdbc { type Seq[+A] = scala.collection.immutable.Seq[A] val Seq = scala.collection.immutable.Seq type List[+A] = scala.collection.immutable.List[A] val List = scala.collection.immutable.List implicit class RowData(rs: ResultSet) { def apply(columnNumber: Int): Any = rs.getObject(columnNumber) def apply(columnName: String): Any = rs.getObject(columnName) def toIterator[E](rowMapper: ResultSet => E): Iterator[E] = new Iterator[E Note that I don't want to use getOrElseUpdate here if I don't have to because it gets pretty verbose when you have nested maps and obscures what's actually going on in the code: m.getOrElseUpdate(1992, Map[String, Set[String]]()).getOrElseUpdate("foo", Set[String]()) ++= "bar" So I'm overriding HashMap's "default" method.
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* This is equivalent to FutureConverters.toScala(this), however, it converts the wrapped completion stage to * a future rather than this, which means if the wrapped completion stage itself wraps a Scala future, it will * simply return that wrapped future. * * @return A Scala future that is completed when this promise is completed. */ public at scala.collection.mutable.AbstractMap.getOrElseUpdate(Map.scala:91) Could you please advise how to overcome the error? Reply. Valentin Nikotin.

Scala’s Predef object offers an implicit conversion that lets you write key -> value as an alternate syntax ms getOrElseUpdate (k, d) If key k is defined in map But the method getOrElseUpdate of scala.co The ScalaDoc states that a scala.collection.concurrent.TrieMap is thread-safe: A concurrent hash-trie or TrieMap is a concurrent thread-safe lock-free implementation of a hash array mapped trie. Bu If there is a difference, I still wouldn't expect it to necessarily work out in favor of using Java for Scala (and vice-versa, I suppose): by removing the Scala code from a more normal context, you might make the microbenchmarking results even less relevant to normal usage than microbenchmarks usually are. If you use recursive getOrElseUpdate you can easily end up with a map that contains the same key twice with different values: val map = mutable. Map [ String, String ] () map.getOrElseUpdate ("key", { map.getOrElseUpdate ("key", "value1") "value2" }) map The second call could come from another place in the application this is just a sample.
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Note: getOrElseUpdate is not an atomic operation in EhCache and is implemented as a get followed by computing the value, then a set. This means it’s possible for the value to be computed multiple times if multiple threads are calling getOrElse simultaneously.

UnsatisfiedLinkError: /mxnet/scala-package/init-native/linux-x86_64/target/libmxnet-init-scala getOrElseUpdate(MapLike.scala:194) [INFO] at  getOrElseUpdate(Map.scala:82) [INFO] at scala.reflect.macros.runtime.MacroRuntimes.standardMacroRuntime(MacroRuntimes.scala:50)  getOrElseUpdate$(MapLike.scala:203) [error] at scala.collection.mutable.AbstractMap.getOrElseUpdate(Map.scala:80) [error] at scala.reflect.macros.runtime. TypeAnalyzer$UDTAnalyzerInstance$UDTAnalyzerCache$$anonfun$getOrElseUpdate$2$$anonfun$apply$4.apply(TypeAnalyzer.scala:481)  getOrElseUpdate(Map.scala:80) [error] at scala.reflect.macros.runtime.MacroRuntimes.standardMacroRuntime(MacroRuntimes.scala:38)  getOrElseUpdate(Map.scala:80). [error] at scala.reflect.macros.runtime.MacroRuntimes.standardMacroRuntime(MacroRuntimes.scala:38). Jag är ny på scala. Som titel import scala.collection.mutable val map = mutable.

.getOrElseUpdate makes it convenient to use a mutable Map as a cache: the second parameter to .getOrElseUpdate is a lazy "by-name" parameter, and is only evaluated when the key is not found in the Map. This provides the common "check if key present, if so return value, otherwise insert new value and return that" workflow built in.

If the above query returns a non-empty dataset then the problem is caused by the Request type returned by the query. Resolution. Remove these request types or add at least one field to the request type. Play Framework - The High Velocity Web Framework For Java and Scala. Note : getOrElseUpdate is not an atomic operation in EhCache and is implemented  Scala parallel collections allow you to solve data parallelism problems in ms getOrElseUpdate(k, d), If key k is defined in map ms, return its associated value. scala> Map('a' -> 1, 'b' -> 2) res4: scala.collection.immutable.Map[Char getOrElseUpdate(2, 3) res54: Int = 3 scala> numbers res55: scala.collection. mutable.

github上 tispark示例运行失败，com.pingcap   Functional Relational Mapping for Scala · Scala. Seamless data access for your Scala application — Write Scala code to query your database. · Type Safe.