fix stupid and dangerous bugs with sleeps not working

respodns/dns.py

@@ -193,17 +193,17 @@ async def try_all_ips(db, try_me, checks, opts: Options, callback=None):
     from asyncio import create_task, sleep, BoundedSemaphore
 
     seen, total = 0, None
+    sem = BoundedSemaphore(opts.ip_simul)
 
-    async def process(ip):
+    async def _process(ip):
         nonlocal seen
-        first = seen == 0
         seen += 1
         if opts.progress:
             lament(f"#{seen}: {ip}" if total is None else f"#{seen}/{total}: {ip}")
             stderr.flush()
-        if not first:
-            await sleep(opts.ip_wait)
+
         first_failure = await try_ip(db, ip, checks, opts, callback)
+
         if first_failure is None:
             print(ip)  # all tests for this server passed; pass it along to stdout
         elif opts.dry:  # don't save the error anywhere; pass it along to stdout
@@ -214,14 +214,23 @@ async def try_all_ips(db, try_me, checks, opts: Options, callback=None):
             else:
                 print(ip, ff.reason, ff.kind, ff.domain, sep="\t")
 
-    sem = BoundedSemaphore(opts.ip_simul)
+    async def process(ip):
+        try:
+            await _process(ip)
+        finally:
+            sem.release()
+
     tasks = []
     while (res := await try_me.get()) is not None:
-        ip, total = res
         #lament("TRYING", ip)
-        async with sem:
-            task = create_task(process(ip))
-            tasks.append(task)
+        if len(tasks) > 0:
+            await sleep(opts.ip_wait)
+        ip, total = res
+        # acquire now instead of within the task so
+        # a ton of tasks aren't created all at once.
+        await sem.acquire()
+        task = create_task(process(ip))
+        tasks.append(task)
     for task in tasks:
         await task