diff -r 25e923c57af7 -r 68a7ad1385bc src/Pure/Tools/build_process.scala
--- a/src/Pure/Tools/build_process.scala	Sat Feb 11 23:24:57 2023 +0100
+++ b/src/Pure/Tools/build_process.scala	Sun Feb 12 13:45:06 2023 +0100
@@ -9,6 +9,8 @@
 
 
 import scala.math.Ordering
+import scala.collection.immutable.SortedSet
+import scala.annotation.tailrec
 
 
 object Build_Process {
@@ -64,10 +66,11 @@
 
   object Context {
     def apply(
-      sessions_structure: Sessions.Structure,
       store: Sessions.Store,
+      deps: Sessions.Deps,
       progress: Progress = new Progress
     ): Context = {
+      val sessions_structure = deps.sessions_structure
       val build_graph = sessions_structure.build_graph
 
       val sessions =
@@ -110,19 +113,250 @@
             }
         }
 
-      new Context(sessions_structure, sessions, ordering)
+      new Context(store, deps, sessions, ordering, progress)
     }
   }
 
   final class Context private(
-    val sessions_structure: Sessions.Structure,
+    val store: Sessions.Store,
+    val deps: Sessions.Deps,
     sessions: Map[String, Session_Context],
-    val ordering: Ordering[String]
+    val ordering: Ordering[String],
+    val progress: Progress
   ) {
+    def sessions_structure: Sessions.Structure = deps.sessions_structure
+
     def apply(session: String): Session_Context =
       sessions.getOrElse(session, Session_Context.empty(session, Time.zero))
 
     def build_heap(session: String): Boolean =
       Sessions.is_pure(session) || !sessions_structure.build_graph.is_maximal(session)
   }
+
+
+  /* queue with scheduling information */
+
+  private object Queue {
+    def apply(build_context: Build_Process.Context): Queue = {
+      val build_graph = build_context.sessions_structure.build_graph
+      val build_order = SortedSet.from(build_graph.keys)(build_context.ordering)
+      new Queue(build_graph, build_order)
+    }
+  }
+
+  private class Queue(
+    build_graph: Graph[String, Sessions.Info],
+    build_order: SortedSet[String]
+  ) {
+    def is_empty: Boolean = build_graph.is_empty
+
+    def - (name: String): Queue =
+      new Queue(build_graph.del_node(name), build_order - name)
+
+    def dequeue(skip: String => Boolean): Option[String] =
+      build_order.iterator.dropWhile(name => skip(name) || !build_graph.is_minimal(name))
+        .nextOption()
+  }
+
+
+  /* main */
+
+  private def session_finished(session_name: String, process_result: Process_Result): String =
+    "Finished " + session_name + " (" + process_result.timing.message_resources + ")"
+
+  private def session_timing(session_name: String, build_log: Build_Log.Session_Info): String = {
+    val props = build_log.session_timing
+    val threads = Markup.Session_Timing.Threads.unapply(props) getOrElse 1
+    val timing = Markup.Timing_Properties.get(props)
+    "Timing " + session_name + " (" + threads + " threads, " + timing.message_factor + ")"
+  }
+
+  case class Result(
+    current: Boolean,
+    output_heap: SHA1.Shasum,
+    process_result: Process_Result
+  ) {
+    def ok: Boolean = process_result.ok
+  }
+
+  def main(
+    build_context: Context,
+    build_heap: Boolean = false,
+    numa_shuffling: Boolean = false,
+    max_jobs: Int = 1,
+    fresh_build: Boolean = false,
+    no_build: Boolean = false,
+    verbose: Boolean = false,
+    session_setup: (String, Session) => Unit = (_, _) => ()
+  ): Map[String, Result] = {
+    val store = build_context.store
+    val build_options = store.options
+    val build_deps = build_context.deps
+    val progress = build_context.progress
+
+    def sleep(): Unit =
+      Isabelle_Thread.interrupt_handler(_ => progress.stop()) {
+        build_options.seconds("editor_input_delay").sleep()
+      }
+
+    val log =
+      build_options.string("system_log") match {
+        case "" => No_Logger
+        case "-" => Logger.make(progress)
+        case log_file => Logger.make(Some(Path.explode(log_file)))
+      }
+
+    val numa_nodes = new NUMA.Nodes(numa_shuffling)
+
+    @tailrec def loop(
+      pending: Queue,
+      running: Map[String, (SHA1.Shasum, Build_Job)],
+      results: Map[String, Result]
+    ): Map[String, Result] = {
+      def used_node(i: Int): Boolean =
+        running.iterator.exists(
+          { case (_, (_, job)) => job.numa_node.isDefined && job.numa_node.get == i })
+
+      if (pending.is_empty) results
+      else {
+        if (progress.stopped) {
+          for ((_, (_, job)) <- running) job.terminate()
+        }
+
+        running.find({ case (_, (_, job)) => job.is_finished }) match {
+          case Some((session_name, (input_heaps, job))) =>
+            //{{{ finish job
+
+            val process_result = job.join
+
+            val output_heap =
+              if (process_result.ok && job.do_store && store.output_heap(session_name).is_file) {
+                SHA1.shasum(ML_Heap.write_digest(store.output_heap(session_name)), session_name)
+              }
+              else SHA1.no_shasum
+
+            val log_lines = process_result.out_lines.filterNot(Protocol_Message.Marker.test)
+            val process_result_tail = {
+              val tail = job.info.options.int("process_output_tail")
+              process_result.copy(
+                out_lines =
+                  "(more details via \"isabelle log -H Error " + session_name + "\")" ::
+                  (if (tail == 0) log_lines else log_lines.drop(log_lines.length - tail max 0)))
+            }
+
+            val build_log =
+              Build_Log.Log_File(session_name, process_result.out_lines).
+                parse_session_info(
+                  command_timings = true,
+                  theory_timings = true,
+                  ml_statistics = true,
+                  task_statistics = true)
+
+            // write log file
+            if (process_result.ok) {
+              File.write_gzip(store.output_log_gz(session_name), terminate_lines(log_lines))
+            }
+            else File.write(store.output_log(session_name), terminate_lines(log_lines))
+
+            // write database
+            using(store.open_database(session_name, output = true))(db =>
+              store.write_session_info(db, session_name, job.session_sources,
+                build_log =
+                  if (process_result.timeout) build_log.error("Timeout") else build_log,
+                build =
+                  Build.Session_Info(build_deps.sources_shasum(session_name), input_heaps,
+                    output_heap, process_result.rc, UUID.random().toString)))
+
+            // messages
+            process_result.err_lines.foreach(progress.echo)
+
+            if (process_result.ok) {
+              if (verbose) progress.echo(session_timing(session_name, build_log))
+              progress.echo(session_finished(session_name, process_result))
+            }
+            else {
+              progress.echo(session_name + " FAILED")
+              if (!process_result.interrupted) progress.echo(process_result_tail.out)
+            }
+
+            loop(pending - session_name, running - session_name,
+              results + (session_name -> Result(false, output_heap, process_result_tail)))
+            //}}}
+          case None if running.size < (max_jobs max 1) =>
+            //{{{ check/start next job
+            pending.dequeue(running.isDefinedAt) match {
+              case Some(session_name) =>
+                val ancestor_results =
+                  build_deps.sessions_structure.build_requirements(List(session_name)).
+                    filterNot(_ == session_name).map(results(_))
+                val input_heaps =
+                  if (ancestor_results.isEmpty) {
+                    SHA1.shasum_meta_info(SHA1.digest(Path.explode("$POLYML_EXE")))
+                  }
+                  else SHA1.flat_shasum(ancestor_results.map(_.output_heap))
+
+                val do_store = build_heap || build_context.build_heap(session_name)
+                val (current, output_heap) = {
+                  store.try_open_database(session_name) match {
+                    case Some(db) =>
+                      using(db)(store.read_build(_, session_name)) match {
+                        case Some(build) =>
+                          val output_heap = store.find_heap_shasum(session_name)
+                          val current =
+                            !fresh_build &&
+                            build.ok &&
+                            build.sources == build_deps.sources_shasum(session_name) &&
+                            build.input_heaps == input_heaps &&
+                            build.output_heap == output_heap &&
+                            !(do_store && output_heap.is_empty)
+                          (current, output_heap)
+                        case None => (false, SHA1.no_shasum)
+                      }
+                    case None => (false, SHA1.no_shasum)
+                  }
+                }
+                val all_current = current && ancestor_results.forall(_.current)
+
+                if (all_current) {
+                  loop(pending - session_name, running,
+                    results + (session_name -> Result(true, output_heap, Process_Result.ok)))
+                }
+                else if (no_build) {
+                  progress.echo_if(verbose, "Skipping " + session_name + " ...")
+                  loop(pending - session_name, running,
+                    results + (session_name -> Result(false, output_heap, Process_Result.error)))
+                }
+                else if (ancestor_results.forall(_.ok) && !progress.stopped) {
+                  progress.echo((if (do_store) "Building " else "Running ") + session_name + " ...")
+
+                  store.clean_output(session_name)
+                  using(store.open_database(session_name, output = true))(
+                    store.init_session_info(_, session_name))
+
+                  val session_background = build_deps.background(session_name)
+                  val resources =
+                    new Resources(session_background, log = log,
+                      command_timings = build_context(session_name).old_command_timings)
+
+                  val numa_node = numa_nodes.next(used_node)
+                  val job =
+                    new Build_Job(progress, session_background, store, do_store,
+                      resources, session_setup, numa_node)
+                  loop(pending, running + (session_name -> (input_heaps, job)), results)
+                }
+                else {
+                  progress.echo(session_name + " CANCELLED")
+                  loop(pending - session_name, running,
+                    results + (session_name -> Result(false, output_heap, Process_Result.undefined)))
+                }
+              case None => sleep(); loop(pending, running, results)
+            }
+            ///}}}
+          case None => sleep(); loop(pending, running, results)
+        }
+      }
+    }
+
+    loop(Queue(build_context), Map.empty, Map.empty)
+  }
 }