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Expose more granular wait event data to the user (#9163)

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In PG17, there is this newfangled custom wait events system. This commit
adds that feature to Neon, so that users can see what their backends may
be waiting for when a PostgreSQL backend is playing the waiting game in
Neon code.
This commit is contained in:
Matthias van de Meent
2024-10-02 11:12:50 +02:00
committed by GitHub
parent 2e3b7862d0
commit ea32f1d0a3
5 changed files with 85 additions and 6 deletions
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8
pgxn/neon/file_cache.c
View File

@@ -42,6 +42,7 @@
#include "hll.h"
#include "bitmap.h"
#include "neon.h"
#define CriticalAssert(cond) do if (!(cond)) elog(PANIC, "Assertion %s failed at %s:%d: ", #cond, __FILE__, __LINE__); while (0)
@@ -173,7 +174,9 @@ lfc_disable(char const *op)
* If the reason of error is ENOSPC, then truncation of file may
* help to reclaim some space
*/
pgstat_report_wait_start(WAIT_EVENT_NEON_LFC_TRUNCATE);
int rc = ftruncate(lfc_desc, 0);
pgstat_report_wait_end();
if (rc < 0)
elog(WARNING, "Failed to truncate local file cache %s: %m", lfc_path);
@@ -769,8 +772,10 @@ lfc_readv_select(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
if (iteration_hits != 0)
{
pgstat_report_wait_start(WAIT_EVENT_NEON_LFC_READ);
rc = preadv(lfc_desc, iov, blocks_in_chunk,
((off_t) entry_offset * BLOCKS_PER_CHUNK + chunk_offs) * BLCKSZ);
pgstat_report_wait_end();
if (rc != (BLCKSZ * blocks_in_chunk))
{
@@ -944,8 +949,11 @@ lfc_writev(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
lfc_ctl->writes += blocks_in_chunk;
LWLockRelease(lfc_lock);
pgstat_report_wait_start(WAIT_EVENT_NEON_LFC_WRITE);
rc = pwritev(lfc_desc, iov, blocks_in_chunk,
((off_t) entry_offset * BLOCKS_PER_CHUNK + chunk_offs) * BLCKSZ);
pgstat_report_wait_end();
if (rc != BLCKSZ * blocks_in_chunk)
{
lfc_disable("write");

13
pgxn/neon/libpagestore.c
View File

@@ -490,7 +490,7 @@ pageserver_connect(shardno_t shard_no, int elevel)
WL_EXIT_ON_PM_DEATH | WL_LATCH_SET | WL_SOCKET_READABLE,
PQsocket(shard->conn),
0,
PG_WAIT_EXTENSION);
WAIT_EVENT_NEON_PS_STARTING);
elog(DEBUG5, "PGRES_POLLING_READING=>%d", rc);
if (rc & WL_LATCH_SET)
{
@@ -512,7 +512,7 @@ pageserver_connect(shardno_t shard_no, int elevel)
WL_EXIT_ON_PM_DEATH | WL_LATCH_SET | WL_SOCKET_WRITEABLE,
PQsocket(shard->conn),
0,
PG_WAIT_EXTENSION);
WAIT_EVENT_NEON_PS_STARTING);
elog(DEBUG5, "PGRES_POLLING_WRITING=>%d", rc);
if (rc & WL_LATCH_SET)
{
@@ -608,7 +608,8 @@ pageserver_connect(shardno_t shard_no, int elevel)
WaitEvent event;
/* Sleep until there's something to do */
(void) WaitEventSetWait(shard->wes_read, -1L, &event, 1, PG_WAIT_EXTENSION);
(void) WaitEventSetWait(shard->wes_read, -1L, &event, 1,
WAIT_EVENT_NEON_PS_CONFIGURING);
ResetLatch(MyLatch);
CHECK_FOR_INTERRUPTS();
@@ -656,7 +657,8 @@ static int
call_PQgetCopyData(shardno_t shard_no, char **buffer)
{
int ret;
PGconn *pageserver_conn = page_servers[shard_no].conn;
PageServer *shard = &page_servers[shard_no];
PGconn *pageserver_conn = shard->conn;
retry:
ret = PQgetCopyData(pageserver_conn, buffer, 1 /* async */ );
@@ -666,7 +668,8 @@ retry:
WaitEvent event;
/* Sleep until there's something to do */
(void) WaitEventSetWait(page_servers[shard_no].wes_read, -1L, &event, 1, PG_WAIT_EXTENSION);
(void) WaitEventSetWait(shard->wes_read, -1L, &event, 1,
WAIT_EVENT_NEON_PS_READ);
ResetLatch(MyLatch);
CHECK_FOR_INTERRUPTS();

45
pgxn/neon/neon.c
View File

@@ -41,6 +41,9 @@
#include "pagestore_client.h"
#include "control_plane_connector.h"
#include "walsender_hooks.h"
#if PG_MAJORVERSION_NUM >= 16
#include "storage/ipc.h"
#endif
PG_MODULE_MAGIC;
void _PG_init(void);
@@ -49,6 +52,23 @@ static int logical_replication_max_snap_files = 300;
static int running_xacts_overflow_policy;
#if PG_MAJORVERSION_NUM >= 16
static shmem_startup_hook_type prev_shmem_startup_hook;
static void neon_shmem_startup_hook(void);
#endif
#if PG_MAJORVERSION_NUM >= 17
uint32 WAIT_EVENT_NEON_LFC_MAINTENANCE;
uint32 WAIT_EVENT_NEON_LFC_READ;
uint32 WAIT_EVENT_NEON_LFC_TRUNCATE;
uint32 WAIT_EVENT_NEON_LFC_WRITE;
uint32 WAIT_EVENT_NEON_PS_STARTING;
uint32 WAIT_EVENT_NEON_PS_CONFIGURING;
uint32 WAIT_EVENT_NEON_PS_SEND;
uint32 WAIT_EVENT_NEON_PS_READ;
uint32 WAIT_EVENT_NEON_WAL_DL;
#endif
enum RunningXactsOverflowPolicies {
OP_IGNORE,
OP_SKIP,
@@ -635,6 +655,9 @@ _PG_init(void)
*/
#if PG_VERSION_NUM >= 160000
load_file("$libdir/neon_rmgr", false);
prev_shmem_startup_hook = shmem_startup_hook;
shmem_startup_hook = neon_shmem_startup_hook;
#endif
pg_init_libpagestore();
@@ -721,3 +744,25 @@ backpressure_throttling_time(PG_FUNCTION_ARGS)
{
PG_RETURN_UINT64(BackpressureThrottlingTime());
}
#if PG_MAJORVERSION_NUM >= 16
static void
neon_shmem_startup_hook(void)
{
/* Initialize */
if (prev_shmem_startup_hook)
prev_shmem_startup_hook();
#if PG_PG_MAJORVERSION_NUM >= 17
WAIT_EVENT_NEON_LFC_MAINTENANCE = WaitEventExtensionNew("Neon/FileCache_Maintenance");
WAIT_EVENT_NEON_LFC_READ = WaitEventExtensionNew("Neon/FileCache_Read");
WAIT_EVENT_NEON_LFC_TRUNCATE = WaitEventExtensionNew("Neon/FileCache_Truncate");
WAIT_EVENT_NEON_LFC_WRITE = WaitEventExtensionNew("Neon/FileCache_Write");
WAIT_EVENT_NEON_PS_STARTING = WaitEventExtensionNew("Neon/PS_Starting");
WAIT_EVENT_NEON_PS_CONFIGURING = WaitEventExtensionNew("Neon/PS_Configuring");
WAIT_EVENT_NEON_PS_SEND = WaitEventExtensionNew("Neon/PS_SendIO");
WAIT_EVENT_NEON_PS_READ = WaitEventExtensionNew("Neon/PS_ReadIO");
WAIT_EVENT_NEON_WAL_DL = WaitEventExtensionNew("Neon/WAL_Download");
#endif
}
#endif

23
pgxn/neon/neon.h
View File

@@ -12,6 +12,7 @@
#ifndef NEON_H
#define NEON_H
#include "access/xlogreader.h"
#include "utils/wait_event.h"
/* GUCs */
extern char *neon_auth_token;
@@ -22,6 +23,28 @@ extern char *wal_acceptors_list;
extern int wal_acceptor_reconnect_timeout;
extern int wal_acceptor_connection_timeout;
#if PG_MAJORVERSION_NUM >= 17
extern uint32 WAIT_EVENT_NEON_LFC_MAINTENANCE;
extern uint32 WAIT_EVENT_NEON_LFC_READ;
extern uint32 WAIT_EVENT_NEON_LFC_TRUNCATE;
extern uint32 WAIT_EVENT_NEON_LFC_WRITE;
extern uint32 WAIT_EVENT_NEON_PS_STARTING;
extern uint32 WAIT_EVENT_NEON_PS_CONFIGURING;
extern uint32 WAIT_EVENT_NEON_PS_SEND;
extern uint32 WAIT_EVENT_NEON_PS_READ;
extern uint32 WAIT_EVENT_NEON_WAL_DL;
#else
#define WAIT_EVENT_NEON_LFC_MAINTENANCE PG_WAIT_EXTENSION
#define WAIT_EVENT_NEON_LFC_READ WAIT_EVENT_BUFFILE_READ
#define WAIT_EVENT_NEON_LFC_TRUNCATE WAIT_EVENT_BUFFILE_TRUNCATE
#define WAIT_EVENT_NEON_LFC_WRITE WAIT_EVENT_BUFFILE_WRITE
#define WAIT_EVENT_NEON_PS_STARTING PG_WAIT_EXTENSION
#define WAIT_EVENT_NEON_PS_CONFIGURING PG_WAIT_EXTENSION
#define WAIT_EVENT_NEON_PS_SEND PG_WAIT_EXTENSION
#define WAIT_EVENT_NEON_PS_READ PG_WAIT_EXTENSION
#define WAIT_EVENT_NEON_WAL_DL WAIT_EVENT_WAL_READ
#endif
extern void pg_init_libpagestore(void);
extern void pg_init_walproposer(void);

2
pgxn/neon/walsender_hooks.c
View File

@@ -160,7 +160,7 @@ NeonWALPageRead(
WL_LATCH_SET | WL_EXIT_ON_PM_DEATH | reader_events,
sock,
timeout_ms,
WAIT_EVENT_WAL_SENDER_MAIN);
WAIT_EVENT_NEON_WAL_DL);
}
}
}