Remove incompatible parallelization (fixes #255)

Unfortunately the GPars trick is not safe, causing deadlocks with other
plugins. The safest solution is to remove and eventually use newer
Gradle apis that expose some parallel support. The core performance
issue, though, is that Gradle does not resolve dependencies in parallel
so doing project & configurations was a marginal gain.

.gitignore

@@ -5,6 +5,7 @@ out
 .settings
 .project
 .gradle
+.vscode/
 .idea/
 *.iml
 *.ipr

build.gradle

@@ -24,7 +24,7 @@ apply plugin: 'nexus'
 apply plugin: 'codenarc'
 
 group = 'com.github.ben-manes'
-version = '0.20.0'
+version = '0.21.0'
 
 sourceCompatibility = '1.6'
 
@@ -52,8 +52,7 @@ dependencies {
   compile gradleApi()
   compile localGroovy()
 
-  compile 'com.thoughtworks.xstream:xstream:1.4.10',
-          'org.codehaus.gpars:gpars:1.2.1'
+  compile 'com.thoughtworks.xstream:xstream:1.4.10'
   testCompile gradleTestKit()
   testCompile('org.spockframework:spock-core:1.0-groovy-2.4') {
     exclude(module: 'groovy-all')

src/main/groovy/com/github/benmanes/gradle/versions/updates/DependencyUpdates.groovy

@@ -18,7 +18,6 @@ package com.github.benmanes.gradle.versions.updates
 import com.github.benmanes.gradle.versions.updates.gradle.GradleUpdateChecker
 import groovy.transform.TupleConstructor
 import groovy.transform.TypeChecked
-import groovyx.gpars.GParsPool
 import org.gradle.api.Project
 import org.gradle.api.artifacts.Configuration
 import org.gradle.api.artifacts.UnresolvedDependency
@@ -52,7 +51,7 @@ class DependencyUpdates {
     Map<Project, Set<Configuration>> projectConfigs = project.allprojects.collectEntries { proj ->
       [proj, proj.configurations.plus(proj.buildscript.configurations) as Set]
     }
-    Set<DependencyStatus> status = resolveInParallel(projectConfigs)
+    Set<DependencyStatus> status = resolveProjects(projectConfigs)
 
     VersionMapping versions = new VersionMapping(project, status)
     Set<UnresolvedDependency> unresolved =
@@ -63,22 +62,14 @@ class DependencyUpdates {
     return createReporter(versions, unresolved, projectUrls)
   }
 
-  @TypeChecked(SKIP)
-  private Set<DependencyStatus> resolveInParallel(Map<Project, Set<Configuration>> projectConfigs) {
-    int numberOfThreads = Math.min((int) 1.5 * Runtime.getRuntime().availableProcessors(),
-      projectConfigs.values().collect { it.size() }.sum())
-    def pool = GParsPool.createPool(numberOfThreads)
-    return GParsPool.withExistingPool(pool) {
-      projectConfigs.keySet().collectParallel { proj ->
-        Set<Configuration> configurations = projectConfigs.get(proj)
-        Resolver resolver = new Resolver(proj, resolutionStrategy, pool)
-        GParsPool.withExistingPool(pool) {
-          configurations.collectParallel { Configuration config ->
-            resolve(resolver, proj, config)
-          }.flatten() as Set<DependencyStatus>
-        }
+  private Set<DependencyStatus> resolveProjects(Map<Project, Set<Configuration>> projectConfigs) {
+    projectConfigs.keySet().collect { proj ->
+      Set<Configuration> configurations = projectConfigs.get(proj)
+      Resolver resolver = new Resolver(proj, resolutionStrategy)
+      configurations.collect { Configuration config ->
+        resolve(resolver, proj, config)
       }.flatten() as Set<DependencyStatus>
-    }
+    }.flatten() as Set<DependencyStatus>
   }
 
   private Set<DependencyStatus> resolve(Resolver resolver, Project proj, Configuration config) {

src/main/groovy/com/github/benmanes/gradle/versions/updates/Resolver.groovy

@@ -16,7 +16,6 @@
 package com.github.benmanes.gradle.versions.updates
 
 import groovy.transform.TypeChecked
-import groovyx.gpars.GParsPool
 import java.util.concurrent.ConcurrentMap
 import java.util.concurrent.ConcurrentHashMap
 import org.gradle.api.Project
@@ -51,18 +50,16 @@ import static org.gradle.api.specs.Specs.SATISFIES_ALL
  */
 @TypeChecked
 class Resolver {
-  final Object pool
   final Project project
   final Closure resolutionStrategy
   final boolean useSelectionRules
   final boolean collectProjectUrls
   final ConcurrentMap<ModuleVersionIdentifier, ProjectUrl> projectUrls
 
-  Resolver(Project project, Closure resolutionStrategy, Object pool) {
+  Resolver(Project project, Closure resolutionStrategy) {
     this.projectUrls = new ConcurrentHashMap<>()
     this.resolutionStrategy = resolutionStrategy
     this.project = project
-    this.pool = pool
 
     useSelectionRules = new VersionComparator(project)
       .compare(project.gradle.gradleVersion, '2.2') >= 0
@@ -84,22 +81,19 @@ class Resolver {
   }
 
   /** Returns the version status of the configuration's dependencies. */
-  @TypeChecked(SKIP)
   private Set<DependencyStatus> getStatus(Map<Coordinate.Key, Coordinate> coordinates,
     Set<ResolvedDependency> resolved, Set<UnresolvedDependency> unresolved) {
-    Set<DependencyStatus> result = Collections.synchronizedSet(new HashSet<>())
-
-    GParsPool.withExistingPool(pool) {
-      resolved.eachParallel { dependency ->
-        Coordinate resolvedCoordinate = Coordinate.from(dependency.module.id)
-        Coordinate originalCoordinate = coordinates.get(resolvedCoordinate.key)
-        Coordinate coord = originalCoordinate ?: resolvedCoordinate
-        if ((originalCoordinate == null) && (resolvedCoordinate.groupId != 'null')) {
-          project.logger.info("Skipping hidden dependency: ${resolvedCoordinate}")
-        } else {
-          String projectUrl = getProjectUrl(dependency.module.id)
-          result.add(new DependencyStatus(coord, resolvedCoordinate.version, projectUrl))
-        }
+    Set<DependencyStatus> result = new HashSet<>()
+
+    resolved.each { dependency ->
+      Coordinate resolvedCoordinate = Coordinate.from(dependency.module.id)
+      Coordinate originalCoordinate = coordinates.get(resolvedCoordinate.key)
+      Coordinate coord = originalCoordinate ?: resolvedCoordinate
+      if ((originalCoordinate == null) && (resolvedCoordinate.groupId != 'null')) {
+        project.logger.info("Skipping hidden dependency: ${resolvedCoordinate}")
+      } else {
+        String projectUrl = getProjectUrl(dependency.module.id)
+        result.add(new DependencyStatus(coord, resolvedCoordinate.version, projectUrl))
       }
     }
     for (UnresolvedDependency dependency : unresolved) {