commit 3b3ea19d2dfb88dd0e3b31338a4b72a1cd0183e2
Author: Anastasia <a.lubennikova@postgrespro.ru>
Date:   Tue Feb 27 17:27:25 2018 +0300

    Reopen logfile and csv logfile on SIGHUP.

diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index f70eea3..54a5bdf 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -306,6 +306,24 @@ SysLoggerMain(int argc, char *argv[])
 		if (got_SIGHUP)
 		{
 			got_SIGHUP = false;
+
+			/* Reopen last logfiles on SIGHUP */
+			if (last_file_name != NULL)
+			{
+				fclose(syslogFile);
+				syslogFile = logfile_open(last_file_name, "a", false);
+				ereport(LOG,
+						(errmsg("Reopen current logfile on SIGHUP")));
+			}
+
+			if (last_csv_file_name != NULL)
+			{
+				fclose(csvlogFile);
+				csvlogFile = logfile_open(last_csv_file_name, "a", false);
+				ereport(LOG,
+						(errmsg("Reopen current CSV logfile on SIGHUP")));
+			}
+
 			ProcessConfigFile(PGC_SIGHUP);
 
 			/*