issue_comments: 1115262218

Here's the full diff I applied to Datasette to get it fully working in Pyodide:

https://github.com/simonw/datasette/compare/94a3171b01fde5c52697aeeff052e3ad4bab5391...8af32bc5b03c30b1f7a4a8cc4bd80eb7e2ee7b81

And as a visible diff:

diff --git a/datasette/app.py b/datasette/app.py
index d269372..6c0c5fc 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -15,7 +15,6 @@ import pkg_resources
 import re
 import secrets
 import sys
-import threading
 import traceback
 import urllib.parse
 from concurrent import futures
@@ -26,7 +25,6 @@ from itsdangerous import URLSafeSerializer
 from jinja2 import ChoiceLoader, Environment, FileSystemLoader, PrefixLoader
 from jinja2.environment import Template
 from jinja2.exceptions import TemplateNotFound
-import uvicorn

 from .views.base import DatasetteError, ureg
 from .views.database import DatabaseDownload, DatabaseView
@@ -813,7 +811,6 @@ class Datasette:
             },
             "datasette": datasette_version,
             "asgi": "3.0",
-            "uvicorn": uvicorn.__version__,
             "sqlite": {
                 "version": sqlite_version,
                 "fts_versions": fts_versions,
@@ -854,23 +851,7 @@ class Datasette:
         ]

     def _threads(self):
-        threads = list(threading.enumerate())
-        d = {
-            "num_threads": len(threads),
-            "threads": [
-                {"name": t.name, "ident": t.ident, "daemon": t.daemon} for t in threads
-            ],
-        }
-        # Only available in Python 3.7+
-        if hasattr(asyncio, "all_tasks"):
-            tasks = asyncio.all_tasks()
-            d.update(
-                {
-                    "num_tasks": len(tasks),
-                    "tasks": [_cleaner_task_str(t) for t in tasks],
-                }
-            )
-        return d
+        return {"num_threads": 0, "threads": []}

     def _actor(self, request):
         return {"actor": request.actor}
diff --git a/datasette/database.py b/datasette/database.py
index ba594a8..b50142d 100644
--- a/datasette/database.py
+++ b/datasette/database.py
@@ -4,7 +4,6 @@ from pathlib import Path
 import janus
 import queue
 import sys
-import threading
 import uuid

 from .tracer import trace
@@ -21,8 +20,6 @@ from .utils import (
 )
 from .inspect import inspect_hash

-connections = threading.local()
-
 AttachedDatabase = namedtuple("AttachedDatabase", ("seq", "name", "file"))


@@ -43,12 +40,12 @@ class Database:
         self.hash = None
         self.cached_size = None
         self._cached_table_counts = None
-        self._write_thread = None
-        self._write_queue = None
         if not self.is_mutable and not self.is_memory:
             p = Path(path)
             self.hash = inspect_hash(p)
             self.cached_size = p.stat().st_size
+        self._read_connection = None
+        self._write_connection = None

     @property
     def cached_table_counts(self):
@@ -134,60 +131,17 @@ class Database:
         return results

     async def execute_write_fn(self, fn, block=True):
-        task_id = uuid.uuid5(uuid.NAMESPACE_DNS, "datasette.io")
-        if self._write_queue is None:
-            self._write_queue = queue.Queue()
-        if self._write_thread is None:
-            self._write_thread = threading.Thread(
-                target=self._execute_writes, daemon=True
-            )
-            self._write_thread.start()
-        reply_queue = janus.Queue()
-        self._write_queue.put(WriteTask(fn, task_id, reply_queue))
-        if block:
-            result = await reply_queue.async_q.get()
-            if isinstance(result, Exception):
-                raise result
-            else:
-                return result
-        else:
-            return task_id
-
-    def _execute_writes(self):
-        # Infinite looping thread that protects the single write connection
-        # to this database
-        conn_exception = None
-        conn = None
-        try:
-            conn = self.connect(write=True)
-            self.ds._prepare_connection(conn, self.name)
-        except Exception as e:
-            conn_exception = e
-        while True:
-            task = self._write_queue.get()
-            if conn_exception is not None:
-                result = conn_exception
-            else:
-                try:
-                    result = task.fn(conn)
-                except Exception as e:
-                    sys.stderr.write("{}\n".format(e))
-                    sys.stderr.flush()
-                    result = e
-            task.reply_queue.sync_q.put(result)
+        # We always treat it as if block=True now
+        if self._write_connection is None:
+            self._write_connection = self.connect(write=True)
+            self.ds._prepare_connection(self._write_connection, self.name)
+        return fn(self._write_connection)

     async def execute_fn(self, fn):
-        def in_thread():
-            conn = getattr(connections, self.name, None)
-            if not conn:
-                conn = self.connect()
-                self.ds._prepare_connection(conn, self.name)
-                setattr(connections, self.name, conn)
-            return fn(conn)
-
-        return await asyncio.get_event_loop().run_in_executor(
-            self.ds.executor, in_thread
-        )
+        if self._read_connection is None:
+            self._read_connection = self.connect()
+            self.ds._prepare_connection(self._read_connection, self.name)
+        return fn(self._read_connection)

     async def execute(
         self,
diff --git a/setup.py b/setup.py
index 7f0562f..c41669c 100644
--- a/setup.py
+++ b/setup.py
@@ -44,20 +44,20 @@ setup(
     install_requires=[
         "asgiref>=3.2.10,<3.6.0",
         "click>=7.1.1,<8.2.0",
-        "click-default-group~=1.2.2",
+        # "click-default-group~=1.2.2",
         "Jinja2>=2.10.3,<3.1.0",
         "hupper~=1.9",
         "httpx>=0.20",
         "pint~=0.9",
         "pluggy>=1.0,<1.1",
-        "uvicorn~=0.11",
+        # "uvicorn~=0.11",
         "aiofiles>=0.4,<0.9",
         "janus>=0.6.2,<1.1",
         "asgi-csrf>=0.9",
         "PyYAML>=5.3,<7.0",
         "mergedeep>=1.1.1,<1.4.0",
         "itsdangerous>=1.1,<3.0",
-        "python-baseconv==1.2.2",
+        # "python-baseconv==1.2.2",
     ],
     entry_points="""
         [console_scripts]