Merge branch 'cassandra-3.11' into cassandra-4.0

doc/scripts/gen-nodetool-docs.py

@@ -24,6 +24,10 @@ import sys
 import subprocess
 from subprocess import PIPE
 from subprocess import Popen
+from itertools import islice
+from threading import Thread
+
+batch_size = 3
 
 if(os.environ.get("SKIP_NODETOOL") == "1"):
     sys.exit(0)
@@ -36,6 +40,16 @@ helpfilename = outdir + "/nodetool.txt"
 command_re = re.compile("(    )([_a-z]+)")
 commandADOCContent = "== {0}\n\n== Usage\n[source,plaintext]\n----\ninclude::example$TEXT/NODETOOL/{0}.txt[]\n----\n"
 
+# https://docs.python.org/3/library/itertools.html#itertools-recipes
+def batched(iterable, n):
+    "Batch data into tuples of length n. The last batch may be shorter."
+    # batched('ABCDEFG', 3) --> ABC DEF G
+    if n < 1:
+        raise ValueError('n must be at least one')
+    it = iter(iterable)
+    while (batch := tuple(islice(it, n))):
+        yield batch
+
 # create the documentation directory
 if not os.path.exists(outdir):
     os.makedirs(outdir)
@@ -78,6 +92,12 @@ with open(outdir + "/nodetool.adoc", "w+") as output:
 
 # create the command usage pages
 with open(helpfilename, "r+") as helpfile:
-    for commandLine in helpfile:
-        command = command_re.match(commandLine)
-        create_adoc(command)
+    for clis in batched(helpfile, batch_size):
+        threads = []
+        for commandLine in clis:
+            command = command_re.match(commandLine)
+            t = Thread(target=create_adoc, args=[command])
+            threads.append(t)
+            t.start()
+        for t in threads:
+            t.join()