From 0da33c762b85aeada111aa1371c33ac6737f8396 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 10 Dec 2019 13:17:08 -0500 Subject: [PATCH] In pg_ctl, work around ERROR_SHARING_VIOLATION on the postmaster log file. On Windows, we use CMD.EXE to redirect the postmaster's stdout/stderr into a log file. CMD.EXE will open that file with non-sharing-friendly parameters, and the file will remain open for a short time after the postmaster has removed postmaster.pid. This can result in an ERROR_SHARING_VIOLATION failure if we attempt to start a new postmaster immediately with the same log file (e.g. during "pg_ctl restart"). This seems to explain intermittent buildfarm failures we've been seeing on Windows machines. To fix, just open and close the log file using our own pgwin32_open(), which will wait if necessary to avoid the failure. (Perhaps someday we should stop using CMD.EXE, but that would be a far more complex patch, and it doesn't seem worth the trouble ... yet.) Back-patch to v12. This only solves the problem when frontend fopen() is redirected to pgwin32_fopen(), which has only been true since commit 0ba06e0bf. Hence, no point in back-patching further, unless we care to back-patch that change too. Diagnosis and patch by Alexander Lakhin (bug #16154). Discussion: https://postgr.es/m/16154-1ccf0b537b24d5e0@postgresql.org --- src/bin/pg_ctl/pg_ctl.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/src/bin/pg_ctl/pg_ctl.c b/src/bin/pg_ctl/pg_ctl.c index 65f9fb4c0a9..b0858411ed9 100644 --- a/src/bin/pg_ctl/pg_ctl.c +++ b/src/bin/pg_ctl/pg_ctl.c @@ -519,8 +519,29 @@ start_postmaster(void) comspec = "CMD"; if (log_file != NULL) + { + /* + * First, touch the log file. The main value of this is that if the + * file is still locked by a previous postmaster run, we'll wait until + * it comes free, instead of failing with ERROR_SHARING_VIOLATION. + * (It'd be better to open the file in a sharing-friendly mode, but we + * can't use CMD.EXE to do that, so work around it. Note that the + * previous postmaster will still have the file open for a short time + * after removing postmaster.pid.) + */ + FILE *fd = fopen(log_file, "a"); + + if (fd == NULL) + { + write_stderr(_("%s: could not create log file \"%s\": %s\n"), + progname, log_file, strerror(errno)); + exit(1); + } + fclose(fd); + snprintf(cmd, MAXPGPATH, "\"%s\" /C \"\"%s\" %s%s < \"%s\" >> \"%s\" 2>&1\"", comspec, exec_path, pgdata_opt, post_opts, DEVNULL, log_file); + } else snprintf(cmd, MAXPGPATH, "\"%s\" /C \"\"%s\" %s%s < \"%s\" 2>&1\"", comspec, exec_path, pgdata_opt, post_opts, DEVNULL); -- 2.39.5