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pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s 7+ messages / 1 participants [nested] [flat]
* pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s @ 2025-10-22 02:29 Fujii Masao <fujii@postgresql.org> 0 siblings, 0 replies; 7+ messages in thread From: Fujii Masao @ 2025-10-22 02:29 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix stalled lag columns in pg_stat_replication when replay LSN stops advancing. Previously, when the replay LSN reported in feedback messages from a standby stopped advancing, for example, due to a recovery conflict, the write_lag and flush_lag columns in pg_stat_replication would initially update but then stop progressing. This prevented users from correctly monitoring replication lag. The problem occurred because when any LSN stopped updating, the lag tracker's cyclic buffer became full (the write head reached the slowest read head). In that state, the lag tracker could no longer compute round-trip lag values correctly. This commit fixes the issue by handling the slowest read entry (the one causing the buffer to fill) as a separate overflow entry and freeing space so the write and other read heads can continue advancing in the buffer. As a result, write_lag and flush_lag now continue updating even if the reported replay LSN remains stalled. Backpatch to all supported versions. Author: Fujii Masao <masao.fujii@gmail.com> Reviewed-by: Chao Li <lic@highgo.com> Reviewed-by: Shinya Kato <shinya11.kato@gmail.com> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com> Discussion: https://postgr.es/m/CAHGQGwGdGQ=1-X-71Caee-LREBUXSzyohkoQJd4yZZCMt24C0g@mail.gmail.com Backpatch-through: 13 Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/883a95646a8e67a2d316f230712ed82b8ba58e28 Modified Files -------------- src/backend/replication/walsender.c | 50 ++++++++++++++++++++++++------------- 1 file changed, 33 insertions(+), 17 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s @ 2025-10-22 02:30 Fujii Masao <fujii@postgresql.org> 0 siblings, 0 replies; 7+ messages in thread From: Fujii Masao @ 2025-10-22 02:30 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix stalled lag columns in pg_stat_replication when replay LSN stops advancing. Previously, when the replay LSN reported in feedback messages from a standby stopped advancing, for example, due to a recovery conflict, the write_lag and flush_lag columns in pg_stat_replication would initially update but then stop progressing. This prevented users from correctly monitoring replication lag. The problem occurred because when any LSN stopped updating, the lag tracker's cyclic buffer became full (the write head reached the slowest read head). In that state, the lag tracker could no longer compute round-trip lag values correctly. This commit fixes the issue by handling the slowest read entry (the one causing the buffer to fill) as a separate overflow entry and freeing space so the write and other read heads can continue advancing in the buffer. As a result, write_lag and flush_lag now continue updating even if the reported replay LSN remains stalled. Backpatch to all supported versions. Author: Fujii Masao <masao.fujii@gmail.com> Reviewed-by: Chao Li <lic@highgo.com> Reviewed-by: Shinya Kato <shinya11.kato@gmail.com> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com> Discussion: https://postgr.es/m/CAHGQGwGdGQ=1-X-71Caee-LREBUXSzyohkoQJd4yZZCMt24C0g@mail.gmail.com Backpatch-through: 13 Branch ------ REL_18_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/9670032cc51f502e39b4b99eba72dd14573d3776 Modified Files -------------- src/backend/replication/walsender.c | 50 ++++++++++++++++++++++++------------- 1 file changed, 33 insertions(+), 17 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s @ 2025-10-22 02:30 Fujii Masao <fujii@postgresql.org> 0 siblings, 0 replies; 7+ messages in thread From: Fujii Masao @ 2025-10-22 02:30 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix stalled lag columns in pg_stat_replication when replay LSN stops advancing. Previously, when the replay LSN reported in feedback messages from a standby stopped advancing, for example, due to a recovery conflict, the write_lag and flush_lag columns in pg_stat_replication would initially update but then stop progressing. This prevented users from correctly monitoring replication lag. The problem occurred because when any LSN stopped updating, the lag tracker's cyclic buffer became full (the write head reached the slowest read head). In that state, the lag tracker could no longer compute round-trip lag values correctly. This commit fixes the issue by handling the slowest read entry (the one causing the buffer to fill) as a separate overflow entry and freeing space so the write and other read heads can continue advancing in the buffer. As a result, write_lag and flush_lag now continue updating even if the reported replay LSN remains stalled. Backpatch to all supported versions. Author: Fujii Masao <masao.fujii@gmail.com> Reviewed-by: Chao Li <lic@highgo.com> Reviewed-by: Shinya Kato <shinya11.kato@gmail.com> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com> Discussion: https://postgr.es/m/CAHGQGwGdGQ=1-X-71Caee-LREBUXSzyohkoQJd4yZZCMt24C0g@mail.gmail.com Backpatch-through: 13 Branch ------ REL_17_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/62d5ee75bbc44c76ca3c6930fc104a96be0f1aa7 Modified Files -------------- src/backend/replication/walsender.c | 50 ++++++++++++++++++++++++------------- 1 file changed, 33 insertions(+), 17 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s @ 2025-10-22 02:31 Fujii Masao <fujii@postgresql.org> 0 siblings, 0 replies; 7+ messages in thread From: Fujii Masao @ 2025-10-22 02:31 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix stalled lag columns in pg_stat_replication when replay LSN stops advancing. Previously, when the replay LSN reported in feedback messages from a standby stopped advancing, for example, due to a recovery conflict, the write_lag and flush_lag columns in pg_stat_replication would initially update but then stop progressing. This prevented users from correctly monitoring replication lag. The problem occurred because when any LSN stopped updating, the lag tracker's cyclic buffer became full (the write head reached the slowest read head). In that state, the lag tracker could no longer compute round-trip lag values correctly. This commit fixes the issue by handling the slowest read entry (the one causing the buffer to fill) as a separate overflow entry and freeing space so the write and other read heads can continue advancing in the buffer. As a result, write_lag and flush_lag now continue updating even if the reported replay LSN remains stalled. Backpatch to all supported versions. Author: Fujii Masao <masao.fujii@gmail.com> Reviewed-by: Chao Li <lic@highgo.com> Reviewed-by: Shinya Kato <shinya11.kato@gmail.com> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com> Discussion: https://postgr.es/m/CAHGQGwGdGQ=1-X-71Caee-LREBUXSzyohkoQJd4yZZCMt24C0g@mail.gmail.com Backpatch-through: 13 Branch ------ REL_16_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/2e55cf4efc8d696c967222a6727698df072b3b67 Modified Files -------------- src/backend/replication/walsender.c | 50 ++++++++++++++++++++++++------------- 1 file changed, 33 insertions(+), 17 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s @ 2025-10-22 02:31 Fujii Masao <fujii@postgresql.org> 0 siblings, 0 replies; 7+ messages in thread From: Fujii Masao @ 2025-10-22 02:31 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix stalled lag columns in pg_stat_replication when replay LSN stops advancing. Previously, when the replay LSN reported in feedback messages from a standby stopped advancing, for example, due to a recovery conflict, the write_lag and flush_lag columns in pg_stat_replication would initially update but then stop progressing. This prevented users from correctly monitoring replication lag. The problem occurred because when any LSN stopped updating, the lag tracker's cyclic buffer became full (the write head reached the slowest read head). In that state, the lag tracker could no longer compute round-trip lag values correctly. This commit fixes the issue by handling the slowest read entry (the one causing the buffer to fill) as a separate overflow entry and freeing space so the write and other read heads can continue advancing in the buffer. As a result, write_lag and flush_lag now continue updating even if the reported replay LSN remains stalled. Backpatch to all supported versions. Author: Fujii Masao <masao.fujii@gmail.com> Reviewed-by: Chao Li <lic@highgo.com> Reviewed-by: Shinya Kato <shinya11.kato@gmail.com> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com> Discussion: https://postgr.es/m/CAHGQGwGdGQ=1-X-71Caee-LREBUXSzyohkoQJd4yZZCMt24C0g@mail.gmail.com Backpatch-through: 13 Branch ------ REL_15_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/59b215f7217f010c945f8371ab905739ebce114d Modified Files -------------- src/backend/replication/walsender.c | 50 ++++++++++++++++++++++++------------- 1 file changed, 33 insertions(+), 17 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s @ 2025-10-22 02:31 Fujii Masao <fujii@postgresql.org> 0 siblings, 0 replies; 7+ messages in thread From: Fujii Masao @ 2025-10-22 02:31 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix stalled lag columns in pg_stat_replication when replay LSN stops advancing. Previously, when the replay LSN reported in feedback messages from a standby stopped advancing, for example, due to a recovery conflict, the write_lag and flush_lag columns in pg_stat_replication would initially update but then stop progressing. This prevented users from correctly monitoring replication lag. The problem occurred because when any LSN stopped updating, the lag tracker's cyclic buffer became full (the write head reached the slowest read head). In that state, the lag tracker could no longer compute round-trip lag values correctly. This commit fixes the issue by handling the slowest read entry (the one causing the buffer to fill) as a separate overflow entry and freeing space so the write and other read heads can continue advancing in the buffer. As a result, write_lag and flush_lag now continue updating even if the reported replay LSN remains stalled. Backpatch to all supported versions. Author: Fujii Masao <masao.fujii@gmail.com> Reviewed-by: Chao Li <lic@highgo.com> Reviewed-by: Shinya Kato <shinya11.kato@gmail.com> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com> Discussion: https://postgr.es/m/CAHGQGwGdGQ=1-X-71Caee-LREBUXSzyohkoQJd4yZZCMt24C0g@mail.gmail.com Backpatch-through: 13 Branch ------ REL_14_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/a7ab6ce6a0fccf016e74794a896508ba2546cce8 Modified Files -------------- src/backend/replication/walsender.c | 50 ++++++++++++++++++++++++------------- 1 file changed, 33 insertions(+), 17 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s @ 2025-10-22 02:31 Fujii Masao <fujii@postgresql.org> 0 siblings, 0 replies; 7+ messages in thread From: Fujii Masao @ 2025-10-22 02:31 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix stalled lag columns in pg_stat_replication when replay LSN stops advancing. Previously, when the replay LSN reported in feedback messages from a standby stopped advancing, for example, due to a recovery conflict, the write_lag and flush_lag columns in pg_stat_replication would initially update but then stop progressing. This prevented users from correctly monitoring replication lag. The problem occurred because when any LSN stopped updating, the lag tracker's cyclic buffer became full (the write head reached the slowest read head). In that state, the lag tracker could no longer compute round-trip lag values correctly. This commit fixes the issue by handling the slowest read entry (the one causing the buffer to fill) as a separate overflow entry and freeing space so the write and other read heads can continue advancing in the buffer. As a result, write_lag and flush_lag now continue updating even if the reported replay LSN remains stalled. Backpatch to all supported versions. Author: Fujii Masao <masao.fujii@gmail.com> Reviewed-by: Chao Li <lic@highgo.com> Reviewed-by: Shinya Kato <shinya11.kato@gmail.com> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com> Discussion: https://postgr.es/m/CAHGQGwGdGQ=1-X-71Caee-LREBUXSzyohkoQJd4yZZCMt24C0g@mail.gmail.com Backpatch-through: 13 Branch ------ REL_13_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/7d7ebdb800fe99ba8fd9b0a1012458856c0d1f3d Modified Files -------------- src/backend/replication/walsender.c | 50 ++++++++++++++++++++++++------------- 1 file changed, 33 insertions(+), 17 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
end of thread, other threads:[~2025-10-22 02:31 UTC | newest] Thread overview: 7+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2025-10-22 02:29 pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s Fujii Masao <fujii@postgresql.org> 2025-10-22 02:30 pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s Fujii Masao <fujii@postgresql.org> 2025-10-22 02:30 pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s Fujii Masao <fujii@postgresql.org> 2025-10-22 02:31 pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s Fujii Masao <fujii@postgresql.org> 2025-10-22 02:31 pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s Fujii Masao <fujii@postgresql.org> 2025-10-22 02:31 pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s Fujii Masao <fujii@postgresql.org> 2025-10-22 02:31 pgsql: Fix stalled lag columns in pg_stat_replication when replay LSN s Fujii Masao <fujii@postgresql.org>
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