From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Sat, 26 Mar 2022 01:32:31 +0000 (+0100)
Subject: docs: add back lost comment and extend it with new knowledge
X-Git-Tag: 3.1~161
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=17df0447961caed07974455835228364ba45c247;p=thirdparty%2Fpsycopg.git

docs: add back lost comment and extend it with new knowledge
---

diff --git a/psycopg/psycopg/generators.py b/psycopg/psycopg/generators.py
index dbee2b2d1..5f8f967fb 100644
--- a/psycopg/psycopg/generators.py
+++ b/psycopg/psycopg/generators.py
@@ -203,6 +203,12 @@ def copy_from(pgconn: PGconn) -> PQGen[Union[memoryview, PGresult]]:
 
 
 def copy_to(pgconn: PGconn, buffer: bytes) -> PQGen[None]:
+    # Retry enqueuing data until successful.
+    #
+    # WARNING! This can cause an infinite loop if the buffer is too large. (see
+    # ticket #255). We avoid it in the Copy object by splitting a large buffer
+    # into smaller ones. We prefer to do it there instead of here in order to
+    # do it upstream the queue decoupling the writer task from the producer one.
     while pgconn.put_copy_data(buffer) == 0:
         yield Wait.W