Skip to content

Remove GVL unlocking at all functions which process data modifiable in a second thread #723

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
larskanis merged 5 commits into from
Sep 18, 2026
Merged

Remove GVL unlocking at all functions which process data modifiable in a second thread #723

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
2aab257
Remove GLV unlocking at all functions which process data modifiable i…
larskanis Jun 7, 2026
0fada47
Add a warning comment to the list of GVL-released functions
larskanis Aug 18, 2026
beb5dd6
Shrink GVL-released libpq functions to necessary only
larskanis Aug 18, 2026
54d9d4d
Move the specs from the previous commit back
larskanis Aug 22, 2026
069eb79
Fix TcpGateSwitcherProcess on Appveyor on Windows
larskanis Sep 17, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions Gemfile
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -20,4 +20,5 @@ group :test do
# With bigdecimal commented out here, corresponding tests are omitted on ruby-3.4+ but are executed on ruby < 3.4.
# That way we can check both situations in CI.
# gem "bigdecimal", "~> 3.0"
gem "drb"
end
198 changes: 39 additions & 159 deletions ext/gvl_wrappers.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -15,12 +15,17 @@
#ifndef __gvl_wrappers_h
#define __gvl_wrappers_h

#include <ruby/version.h>
#include <ruby/thread.h>

#ifdef RUBY_EXTCONF_H
# include RUBY_EXTCONF_H
#endif

#if RUBY_API_VERSION_MAJOR < 4
extern int ruby_thread_has_gvl_p(void);
#endif

#ifndef LIBPQ_HAS_CHUNK_MODE
typedef struct pg_cancel_conn PGcancelConn;
#endif
Expand Down Expand Up @@ -83,20 +88,35 @@ typedef struct pg_cancel_conn PGcancelConn;
}

#ifdef ENABLE_GVL_UNLOCK
#define DEFINE_GVLCB_STUB(name, when_non_void, rettype, lastparamtype, lastparamname) \
rettype gvl_##name(FOR_EACH_PARAM_OF_##name(DEFINE_PARAM_LIST3) lastparamtype lastparamname){ \
struct gvl_wrapper_##name##_params params = { \
{FOR_EACH_PARAM_OF_##name(DEFINE_PARAM_LIST1) lastparamname}, when_non_void((rettype)0) \
}; \
rb_thread_call_with_gvl(gvl_##name##_skeleton, &params); \
when_non_void( return params.retval; ) \
}
#if RUBY_API_VERSION_MAJOR >= 4 || defined(TRUFFLERUBY)
#define DEFINE_GVLCB_STUB(name, when_non_void, rettype, lastparamtype, lastparamname) \
rettype gvl_##name(FOR_EACH_PARAM_OF_##name(DEFINE_PARAM_LIST3) lastparamtype lastparamname){ \
struct gvl_wrapper_##name##_params params = { \
{FOR_EACH_PARAM_OF_##name(DEFINE_PARAM_LIST1) lastparamname}, when_non_void((rettype)0) \
}; \
rb_thread_call_with_gvl(gvl_##name##_skeleton, &params); \
when_non_void( return params.retval; ) \
}
#else
#define DEFINE_GVLCB_STUB(name, when_non_void, rettype, lastparamtype, lastparamname) \
rettype gvl_##name(FOR_EACH_PARAM_OF_##name(DEFINE_PARAM_LIST3) lastparamtype lastparamname){ \
struct gvl_wrapper_##name##_params params = { \
{FOR_EACH_PARAM_OF_##name(DEFINE_PARAM_LIST1) lastparamname}, when_non_void((rettype)0) \
}; \
if (ruby_thread_has_gvl_p()) { \
gvl_##name##_skeleton(&params); \
} else { \
rb_thread_call_with_gvl(gvl_##name##_skeleton, &params); \
} \
when_non_void( return params.retval; ) \
}
#endif
#else
#define DEFINE_GVLCB_STUB(name, when_non_void, rettype, lastparamtype, lastparamname) \
rettype gvl_##name(FOR_EACH_PARAM_OF_##name(DEFINE_PARAM_LIST3) lastparamtype lastparamname){ \
when_non_void( return ) \
name( FOR_EACH_PARAM_OF_##name(DEFINE_PARAM_LIST1) lastparamname ); \
}
#define DEFINE_GVLCB_STUB(name, when_non_void, rettype, lastparamtype, lastparamname) \
rettype gvl_##name(FOR_EACH_PARAM_OF_##name(DEFINE_PARAM_LIST3) lastparamtype lastparamname){ \
when_non_void( return ) \
name( FOR_EACH_PARAM_OF_##name(DEFINE_PARAM_LIST1) lastparamname ); \
}
#endif

#define GVL_TYPE_VOID(string)
Expand All @@ -105,174 +125,34 @@ typedef struct pg_cancel_conn PGcancelConn;

/*
* Definitions of blocking functions and their parameters
*
* ATTENTION:
* Do not GVL-release functions that take pointers to ruby objects.
* If the ruby object is relocated by `GC.compact` from a second thread, before the pointer is used, it is no longer valid.
* That can lead to a crash or to wrong data.
* This issue has been raised in https://github.com/ged/ruby-pg/issues/738 and https://github.com/ged/ruby-pg/issues/721 .
*/

#define FOR_EACH_PARAM_OF_PQconnectdb(param)

#define FOR_EACH_PARAM_OF_PQconnectStart(param)

#define FOR_EACH_PARAM_OF_PQconnectPoll(param)

#define FOR_EACH_PARAM_OF_PQreset(param)

#define FOR_EACH_PARAM_OF_PQresetStart(param)

#define FOR_EACH_PARAM_OF_PQresetPoll(param)

#define FOR_EACH_PARAM_OF_PQping(param)

#define FOR_EACH_PARAM_OF_PQexec(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQexecParams(param) \
param(PGconn *, conn) \
param(const char *, command) \
param(int, nParams) \
param(const Oid *, paramTypes) \
param(const char * const *, paramValues) \
param(const int *, paramLengths) \
param(const int *, paramFormats)

#define FOR_EACH_PARAM_OF_PQexecPrepared(param) \
param(PGconn *, conn) \
param(const char *, stmtName) \
param(int, nParams) \
param(const char * const *, paramValues) \
param(const int *, paramLengths) \
param(const int *, paramFormats)

#define FOR_EACH_PARAM_OF_PQprepare(param) \
param(PGconn *, conn) \
param(const char *, stmtName) \
param(const char *, query) \
param(int, nParams)

#define FOR_EACH_PARAM_OF_PQdescribePrepared(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQdescribePortal(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQclosePrepared(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQclosePortal(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQgetResult(param)

#define FOR_EACH_PARAM_OF_PQputCopyData(param) \
param(PGconn *, conn) \
param(const char *, buffer)

#define FOR_EACH_PARAM_OF_PQputCopyEnd(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQgetCopyData(param) \
param(PGconn *, conn) \
param(char **, buffer)

#define FOR_EACH_PARAM_OF_PQnotifies(param)

#define FOR_EACH_PARAM_OF_PQsendQuery(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQsendQueryParams(param) \
param(PGconn *, conn) \
param(const char *, command) \
param(int, nParams) \
param(const Oid *, paramTypes) \
param(const char *const *, paramValues) \
param(const int *, paramLengths) \
param(const int *, paramFormats)

#define FOR_EACH_PARAM_OF_PQsendPrepare(param) \
param(PGconn *, conn) \
param(const char *, stmtName) \
param(const char *, query) \
param(int, nParams)

#define FOR_EACH_PARAM_OF_PQsendQueryPrepared(param) \
param(PGconn *, conn) \
param(const char *, stmtName) \
param(int, nParams) \
param(const char *const *, paramValues) \
param(const int *, paramLengths) \
param(const int *, paramFormats)

#define FOR_EACH_PARAM_OF_PQsendDescribePrepared(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQsendDescribePortal(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQsendClosePrepared(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQsendClosePortal(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQpipelineSync(param)

#define FOR_EACH_PARAM_OF_PQsendPipelineSync(param)

#define FOR_EACH_PARAM_OF_PQsetClientEncoding(param) \
param(PGconn *, conn)

#define FOR_EACH_PARAM_OF_PQisBusy(param)

#define FOR_EACH_PARAM_OF_PQcancelBlocking(param)
#define FOR_EACH_PARAM_OF_PQcancelStart(param)
#define FOR_EACH_PARAM_OF_PQcancelPoll(param)

#define FOR_EACH_PARAM_OF_PQencryptPasswordConn(param) \
param(PGconn *, conn) \
param(const char *, passwd) \
param(const char *, user)

#define FOR_EACH_PARAM_OF_PQcancel(param) \
param(PGcancel *, cancel) \
param(char *, errbuf)

/* function( name, void_or_nonvoid, returntype, lastparamtype, lastparamname ) */
#define FOR_EACH_BLOCKING_FUNCTION(function) \
function(PQconnectdb, GVL_TYPE_NONVOID, PGconn *, const char *, conninfo) \
function(PQconnectStart, GVL_TYPE_NONVOID, PGconn *, const char *, conninfo) \
function(PQconnectPoll, GVL_TYPE_NONVOID, PostgresPollingStatusType, PGconn *, conn) \
function(PQreset, GVL_TYPE_VOID, void, PGconn *, conn) \
function(PQresetStart, GVL_TYPE_NONVOID, int, PGconn *, conn) \
function(PQresetPoll, GVL_TYPE_NONVOID, PostgresPollingStatusType, PGconn *, conn) \
function(PQping, GVL_TYPE_NONVOID, PGPing, const char *, conninfo) \
function(PQexec, GVL_TYPE_NONVOID, PGresult *, const char *, command) \
function(PQexecParams, GVL_TYPE_NONVOID, PGresult *, int, resultFormat) \
function(PQexecPrepared, GVL_TYPE_NONVOID, PGresult *, int, resultFormat) \
function(PQprepare, GVL_TYPE_NONVOID, PGresult *, const Oid *, paramTypes) \
function(PQdescribePrepared, GVL_TYPE_NONVOID, PGresult *, const char *, stmtName) \
function(PQdescribePortal, GVL_TYPE_NONVOID, PGresult *, const char *, portalName) \
function(PQclosePrepared, GVL_TYPE_NONVOID, PGresult *, const char *, stmtName) \
function(PQclosePortal, GVL_TYPE_NONVOID, PGresult *, const char *, portalName) \
function(PQgetResult, GVL_TYPE_NONVOID, PGresult *, PGconn *, conn) \
function(PQputCopyData, GVL_TYPE_NONVOID, int, int, nbytes) \
function(PQputCopyEnd, GVL_TYPE_NONVOID, int, const char *, errormsg) \
function(PQgetCopyData, GVL_TYPE_NONVOID, int, int, async) \
function(PQnotifies, GVL_TYPE_NONVOID, PGnotify *, PGconn *, conn) \
function(PQsendQuery, GVL_TYPE_NONVOID, int, const char *, query) \
function(PQsendQueryParams, GVL_TYPE_NONVOID, int, int, resultFormat) \
function(PQsendPrepare, GVL_TYPE_NONVOID, int, const Oid *, paramTypes) \
function(PQsendQueryPrepared, GVL_TYPE_NONVOID, int, int, resultFormat) \
function(PQsendDescribePrepared, GVL_TYPE_NONVOID, int, const char *, stmt) \
function(PQsendDescribePortal, GVL_TYPE_NONVOID, int, const char *, portal) \
function(PQsendClosePrepared, GVL_TYPE_NONVOID, int, const char *, stmt) \
function(PQsendClosePortal, GVL_TYPE_NONVOID, int, const char *, portal) \
Comment on lines -259 to -266

@cbandy cbandy Jun 15, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

These are async, and docs describe them as returns 1 if it was able to dispatch the request, and 0 if not. Is it just a socket write? What can block during these?

@larskanis larskanis Jul 24, 2026

Copy link
Copy Markdown
Collaborator Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The PQsend* functions primary allocate and copy the data to be send into libpq's internal buffers. They try to send data, but that isn't enforced. Sending is repeatedly done by other functions, like PQflush or enforced by PQgetResult. So PQsend* functions don't block, unless libpq is broken.

function(PQpipelineSync, GVL_TYPE_NONVOID, int, PGconn *, conn) \
function(PQsendPipelineSync, GVL_TYPE_NONVOID, int, PGconn *, conn) \
function(PQsetClientEncoding, GVL_TYPE_NONVOID, int, const char *, encoding) \
function(PQisBusy, GVL_TYPE_NONVOID, int, PGconn *, conn) \
function(PQcancelBlocking, GVL_TYPE_NONVOID, int, PGcancelConn *, conn) \
function(PQcancelStart, GVL_TYPE_NONVOID, int, PGcancelConn *, conn) \
function(PQcancelPoll, GVL_TYPE_NONVOID, PostgresPollingStatusType, PGcancelConn *, conn) \
function(PQencryptPasswordConn, GVL_TYPE_NONVOID, char *, const char *, algorithm) \
function(PQcancel, GVL_TYPE_NONVOID, int, int, errbufsize);

FOR_EACH_BLOCKING_FUNCTION( DEFINE_GVL_STUB_DECL );

Expand Down
2 changes: 2 additions & 0 deletions ext/pg.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,8 @@ typedef long suseconds_t;

#define pg_gc_location(x) x = rb_gc_location(x)

extern int ruby_native_thread_p(void);

/* For compatibility with ruby < 3.0 */
#ifndef RUBY_TYPED_FROZEN_SHAREABLE
#define PG_RUBY_TYPED_FROZEN_SHAREABLE 0
Expand Down
4 changes: 2 additions & 2 deletions ext/pg_cancel_connection.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -155,7 +155,7 @@ pg_cancon_initialize(VALUE self, VALUE rb_conn)
*
* Requests that the server abandons processing of the current command in a blocking manner.
*
* This method directly calls +PQcancelBlocking+ of libpq, so that it doesn't respond to ruby interrupts and doesn't trigger the +Thread.scheduler+ .
* This method directly calls +PQcancelBlocking+ of libpq, so that it doesn't allow parallel threads, doesn't respond to ruby interrupts and doesn't trigger the +Thread.scheduler+ .
* It is threrfore recommended to call #cancel instead.
*
*/
Expand All @@ -165,7 +165,7 @@ pg_cancon_sync_cancel(VALUE self)
PGcancelConn *conn = pg_cancon_get_conn(self);

pg_cancon_close_socket_io( self );
if(gvl_PQcancelBlocking(conn) == 0)
if(PQcancelBlocking(conn) == 0)
pg_raise_conn_error( rb_eConnectionBad, self, "PQcancelBlocking %s", PQcancelErrorMessage(conn));
return Qnil;
}
Expand Down
Loading
Loading