src/Pure/System/java_statistics.scala

clarified signature (again, see also 8c64e51d9dde and 268bf61631ec);

/*  Title:      Pure/System/java_statistics.scala
    Author:     Makarius

Java runtime statistics.
*/

package isabelle


object Java_Statistics {
  /* memory status */

  sealed case class Memory_Status(heap_size: Long, heap_free: Long) {
    def heap_used: Long = (heap_size - heap_free) max 0
    def heap_used_fraction: Double =
      if (heap_size == 0) 0.0 else heap_used.toDouble / heap_size
  }

  def memory_status(): Memory_Status = {
    val heap_size = Runtime.getRuntime.totalMemory()
    val heap_free = Runtime.getRuntime.freeMemory()
    Memory_Status(heap_size, heap_free)
  }


  /* JVM statistics */

  def jvm_statistics(): Properties.T = {
    val status = memory_status()
    val threads = Thread.activeCount()
    val workers = Isabelle_Thread.pool.getPoolSize
    val workers_active = Isabelle_Thread.pool.getActiveCount

    List(
      "java_heap_size" -> status.heap_size.toString,
      "java_heap_used" -> status.heap_used.toString,
      "java_threads_total" -> threads.toString,
      "java_workers_total" -> workers.toString,
      "java_workers_active" -> workers_active.toString)
  }
}