improve taskexec admin listing performance

README.md

@@ -376,6 +376,7 @@ pre-commit install
   - refactor: removed non-execution related data from the database (clarifying the fact tha the source of truth is the registry)
   - refactor: better support for concurrent workers
   - refactor: better names for models and decorators
+  - refactor: optimise task exec admin listing when `results`, `stdout` or `stderr` holds large data
   - infra: included a demo project
   - infra: improved testing, including for concurrency behaviour
   - infra: updated compatibility to Django 3.2/4.1/4.2 and Python 3.8-3.11

django_toosimple_q/admin.py

@@ -61,7 +61,7 @@ class TaskExecAdmin(ReadOnlyAdmin):
         "started_",
         "finished_",
         "replaced_by_",
-        "result_",
+        "result_preview",
         "task_",
     ]
     list_display_links = ["task_name"]
@@ -96,16 +96,19 @@ class TaskExecAdmin(ReadOnlyAdmin):
         ),
     ]
 
+    def get_queryset(self, request):
+        # defer stdout, stderr and results which may host large values
+        qs = super().get_queryset(request)
+        qs = qs.defer("stdout", "stderr", "result")
+        return qs
+
     def arguments_(self, obj):
         return format_html(
             "{}<br/>{}",
             truncatechars(str(obj.args), 32),
             truncatechars(str(obj.kwargs), 32),
         )
 
-    def result_(self, obj):
-        return truncatechars(str(obj.result), 32)
-
     @admin.display(ordering="due")
     def due_(self, obj):
         return short_naturaltime(obj.due)

django_toosimple_q/migrations/0015_taskexec_result_preview.py

@@ -0,0 +1,29 @@
+# Generated by Django 4.1 on 2024-03-04 15:28
+
+from django.db import migrations, models
+from django.template.defaultfilters import truncatechars
+
+
+def populate_result_preview(apps, schema_editor):
+    # Populate the new result preview field
+    TaskExec = apps.get_model("toosimpleq", "TaskExec")
+    for task_exec in TaskExec.objects.all():
+        task_exec.result_preview = truncatechars(str(task_exec.result), 255)
+        task_exec.save()
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("toosimpleq", "0014_alter_workerstatus_exit_code"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="taskexec",
+            name="result_preview",
+            field=models.CharField(
+                blank=True, editable=False, max_length=255, null=True
+            ),
+        ),
+        migrations.RunPython(populate_result_preview),
+    ]

django_toosimple_q/models.py

@@ -6,6 +6,7 @@
 
 from croniter import croniter, croniter_range
 from django.db import models
+from django.template.defaultfilters import truncatechars
 from django.utils import timezone
 from django.utils.functional import cached_property
 from django.utils.timezone import now
@@ -86,6 +87,9 @@ def done(cls) -> List[str]:
         max_length=32, choices=States.choices, default=States.QUEUED
     )
     result = PickledObjectField(blank=True, null=True)
+    result_preview = models.CharField(
+        max_length=255, blank=True, null=True, editable=False
+    )
     error = models.TextField(blank=True, null=True)
     replaced_by = models.ForeignKey(
         "self", null=True, blank=True, on_delete=models.SET_NULL
@@ -122,6 +126,7 @@ def execute(self):
             stdout, stderr = io.StringIO(), io.StringIO()
             with redirect_stderr(stderr), redirect_stdout(stdout):
                 self.result = task.callable(*self.args, **self.kwargs)
+                self.result_preview = truncatechars(str(self.result), 255)
             logger.info(f"{self} succeeded")
             self.state = TaskExec.States.SUCCEEDED
         except Exception: