Merge pull request #4751 from eatkins/execution-context

Don't use global execution context

main/src/main/scala/sbt/Main.scala

@@ -9,6 +9,7 @@ package sbt
 
 import java.io.{ File, IOException }
 import java.net.URI
+import java.util.concurrent.{ Executors, ForkJoinPool }
 import java.util.concurrent.atomic.AtomicBoolean
 import java.util.{ Locale, Properties }
 
@@ -96,11 +97,21 @@ object StandardMain {
   private[sbt] lazy val exchange = new CommandExchange()
   import scalacache.caffeine._
   private[sbt] lazy val cache: scalacache.Cache[Any] = CaffeineCache[Any]
+  // The access to the pool should be thread safe because lazy val instantiation is thread safe
+  // and pool is only referenced directly in closeRunnable after the executionContext is sure
+  // to have been instantiated
+  private[this] var pool: Option[ForkJoinPool] = None
+  private[sbt] lazy val executionContext: ExecutionContext = ExecutionContext.fromExecutor({
+    val p = new ForkJoinPool
+    pool = Some(p)
+    p
+  })
 
   private[this] val closeRunnable = () => {
     cache.close()(scalacache.modes.sync.mode)
-    cache.close()(scalacache.modes.scalaFuture.mode(ExecutionContext.global))
+    cache.close()(scalacache.modes.scalaFuture.mode(executionContext))
     exchange.shutdown()
+    pool.foreach(_.shutdownNow())
   }
 
   def runManaged(s: State): xsbti.MainResult = {

main/src/main/scala/sbt/internal/DefaultBackgroundJobService.scala

@@ -93,9 +93,9 @@ private[sbt] abstract class AbstractBackgroundJobService extends BackgroundJobSe
       val workingDirectory: File,
       val job: BackgroundJob
   ) extends AbstractJobHandle {
+    implicit val executionContext: ExecutionContext = StandardMain.executionContext
     def humanReadableName: String = job.humanReadableName
     // EC for onStop handler below
-    import ExecutionContext.Implicits.global
     job.onStop { () =>
       // TODO: Fix this
       // logger.close()

main/src/main/scala/sbt/internal/server/Definition.scala

@@ -234,7 +234,7 @@ private[sbt] object Definition {
 
   private[sbt] def getAnalyses: Future[Seq[Analysis]] = {
     import scalacache.modes.scalaFuture._
-    import scala.concurrent.ExecutionContext.Implicits.global
+    implicit val executionContext: ExecutionContext = StandardMain.executionContext
     AnalysesAccess
       .getFrom(StandardMain.cache)
       .collect { case Some(a) => a }

main/src/main/scala/sbt/internal/server/LanguageServerProtocol.scala

@@ -13,7 +13,7 @@ import sjsonnew.JsonFormat
 import sjsonnew.shaded.scalajson.ast.unsafe.JValue
 import sjsonnew.support.scalajson.unsafe.Converter
 import sbt.protocol.Serialization
-import sbt.protocol.{ SettingQuery => Q, CompletionParams => CP }
+import sbt.protocol.{ CompletionParams => CP, SettingQuery => Q }
 import sbt.internal.langserver.{ CancelRequestParams => CRP }
 import sbt.internal.protocol._
 import sbt.internal.protocol.codec._
@@ -21,6 +21,8 @@ import sbt.internal.langserver._
 import sbt.internal.util.ObjectEvent
 import sbt.util.Logger
 
+import scala.concurrent.ExecutionContext
+
 private[sbt] final case class LangServerError(code: Long, message: String)
     extends Throwable(message)
 
@@ -70,7 +72,7 @@ private[sbt] object LanguageServerProtocol {
               jsonRpcRespond(InitializeResult(serverCapabilities), Option(r.id))
 
             case r: JsonRpcRequestMessage if r.method == "textDocument/definition" =>
-              import scala.concurrent.ExecutionContext.Implicits.global
+              implicit val executionContext: ExecutionContext = StandardMain.executionContext
               Definition.lspDefinition(json(r), r.id, CommandSource(name), log)
               ()
             case r: JsonRpcRequestMessage if r.method == "sbt/exec" =>