Add BlockIdManagerSelector (#3560)

Adds the BlockIdManagerSelector to the list of available manager selectors. This selector returns a sorted list of managers by their block id, from greatest (newest) to least (oldest).

docs/reference.rst

@@ -78,6 +78,16 @@ Executors
     parsl.executors.FluxExecutor
     parsl.executors.radical.RadicalPilotExecutor
 
+Manager Selectors
+=================
+
+.. autosummary::
+    :toctree: stubs
+    :nosignatures:
+
+    parsl.executors.high_throughput.manager_selector.RandomManagerSelector
+    parsl.executors.high_throughput.manager_selector.BlockIdManagerSelector
+
 Launchers
 =========
 

parsl/executors/high_throughput/executor.py

@@ -146,6 +146,11 @@
 
     encrypted : bool
         Flag to enable/disable encryption (CurveZMQ). Default is False.
+
+    manager_selector: ManagerSelector
+        Determines what strategy the interchange uses to select managers during task distribution.
+        See API reference under "Manager Selectors" regarding the various manager selectors.
+        Default: 'RandomManagerSelector'
 """  # Documentation for params used by both HTEx and MPIEx
 
 

parsl/executors/high_throughput/manager_selector.py

@@ -19,7 +19,37 @@ def sort_managers(self, ready_managers: Dict[bytes, ManagerRecord], manager_list
 
 class RandomManagerSelector(ManagerSelector):
 
+    """Returns a shuffled list of interesting_managers
+
+    By default this strategy is used by the interchange. Works well
+    in distributing workloads equally across all availble compute
+    resources. The random workload strategy is not effective in
+    conjunction with elastic scaling behavior as the even task
+    distribution does not allow the scaling down of blocks, leading
+    to wasted resource consumption.
+    """
+
     def sort_managers(self, ready_managers: Dict[bytes, ManagerRecord], manager_list: Set[bytes]) -> List[bytes]:
         c_manager_list = list(manager_list)
         random.shuffle(c_manager_list)
         return c_manager_list
+
+
+class BlockIdManagerSelector(ManagerSelector):
+
+    """Returns an interesting_managers list sorted by block ID
+
+    Observations:
+    1. BlockID manager selector helps with workloads that see a varying
+    amount of tasks over time. New blocks are prioritized with the
+    blockID manager selector, when used with 'htex_auto_scaling', results
+    in compute cost savings.
+
+    2. Doesn't really work with bag-of-tasks workloads. When all the tasks
+    are put into the queue upfront, all blocks operate at near full
+    utilization for the majority of the workload, which task goes where
+    doesn't really matter.
+    """
+
+    def sort_managers(self, ready_managers: Dict[bytes, ManagerRecord], manager_list: Set[bytes]) -> List[bytes]:
+        return sorted(manager_list, key=lambda x: (ready_managers[x]['block_id'] is not None, ready_managers[x]['block_id']))

parsl/tests/test_htex/test_block_manager_selector_unit.py

@@ -0,0 +1,20 @@
+import pytest
+
+from parsl.executors.high_throughput.manager_record import ManagerRecord
+from parsl.executors.high_throughput.manager_selector import BlockIdManagerSelector
+
+
+@pytest.mark.local
+def test_sort_managers():
+    ready_managers = {
+        b'manager1': {'block_id': 1},
+        b'manager2': {'block_id': None},
+        b'manager3': {'block_id': 3},
+        b'manager4': {'block_id': 2}
+    }
+
+    manager_list = {b'manager1', b'manager2', b'manager3', b'manager4'}
+    expected_sorted_list = [b'manager2', b'manager1', b'manager4', b'manager3']
+    manager_selector = BlockIdManagerSelector()
+    sorted_managers = manager_selector.sort_managers(ready_managers, manager_list)
+    assert sorted_managers == expected_sorted_list

parsl/tests/test_htex/test_manager_selector_by_block.py

@@ -0,0 +1,53 @@
+import time
+
+import pytest
+
+import parsl
+from parsl.app.app import bash_app, python_app
+from parsl.channels import LocalChannel
+from parsl.config import Config
+from parsl.executors import HighThroughputExecutor
+from parsl.executors.high_throughput.manager_selector import (
+    BlockIdManagerSelector,
+    ManagerSelector,
+)
+from parsl.launchers import WrappedLauncher
+from parsl.providers import LocalProvider
+from parsl.usage_tracking.levels import LEVEL_1
+
+BLOCK_COUNT = 2
+
+
+@parsl.python_app
+def get_worker_pid():
+    import os
+    return os.environ.get('PARSL_WORKER_BLOCK_ID')
+
+
+@pytest.mark.local
+def test_block_id_selection(try_assert):
+    htex = HighThroughputExecutor(
+        label="htex_local",
+        max_workers_per_node=1,
+        manager_selector=BlockIdManagerSelector(),
+        provider=LocalProvider(
+            channel=LocalChannel(),
+            init_blocks=BLOCK_COUNT,
+            max_blocks=BLOCK_COUNT,
+            min_blocks=BLOCK_COUNT,
+        ),
+    )
+
+    config = Config(
+        executors=[htex],
+        usage_tracking=LEVEL_1,
+    )
+
+    with parsl.load(config):
+        blockids = []
+        try_assert(lambda: len(htex.connected_managers()) == BLOCK_COUNT, timeout_ms=20000)
+        for i in range(10):
+            future = get_worker_pid()
+            blockids.append(future.result())
+
+        assert all(blockid == "1" for blockid in blockids)