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Type:
Bug
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Resolution: Unresolved
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Priority:
Major - P3
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None
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Affects Version/s: None
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Component/s: None
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Storage Engines
Background
Wiredtiger calls __conn_session_size during wiredtiger_open to reserve the session slots that threads can use. Currently for eviction workers and lsm_manager workers, we use the configured max threads value, see code below.
static int __conn_session_size(WT_SESSION_IMPL *session, const char *cfg[], uint32_t *vp) { WT_CONFIG_ITEM cval; int64_t v; /* * Start with 25 internal sessions to cover threads the application can't configure (for example, * checkpoint or statistics log server threads). */ #define WT_EXTRA_INTERNAL_SESSIONS 25 v = WT_EXTRA_INTERNAL_SESSIONS; /* Then, add in the thread counts applications can configure. */ WT_RET(__wt_config_gets(session, cfg, "eviction.threads_max", &cval)); v += cval.val; WT_RET(__wt_config_gets(session, cfg, "lsm_manager.worker_thread_max", &cval)); v += cval.val; WT_RET(__wt_config_gets(session, cfg, "session_max", &cval)); v += cval.val; *vp = (uint32_t)v; return (0); }
Problem
Both eviction max worker and lsm_manager max worker can be changed by WT_CONNECTION::reconfigure API, and during the reconfiguration we don't recalculate the number of reserved session slots, causing potential running out of available session slots problem.
Suggested change
For lsm_manager workers we should use the macro WT_LSM_MAX_WORKERS(The max value we can configure for lsm_manager.worker_thread_max) to calculate the session slots. We should do the same for eviction, add a WT_EVICT_MAX_WORKERS in evict.h and use the value to calculate the session slots as well.
diff --git a/src/conn/conn_api.c b/src/conn/conn_api.c index 4ee1d6957..333d2750f 100644 --- a/src/conn/conn_api.c +++ b/src/conn/conn_api.c @@ -2556,11 +2556,9 @@ __conn_session_size(WT_SESSION_IMPL *session, const char *cfg[], uint32_t *vp) v = WT_EXTRA_INTERNAL_SESSIONS; /* Then, add in the thread counts applications can configure. */ - WT_RET(__wt_config_gets(session, cfg, "eviction.threads_max", &cval)); - v += cval.val; + v += WT_EVICT_MAX_WORKERS; - WT_RET(__wt_config_gets(session, cfg, "lsm_manager.worker_thread_max", &cval)); - v += cval.val; + v += WT_LSM_MAX_WORKERS; WT_RET(__wt_config_gets(session, cfg, "session_max", &cval)); v += cval.val; diff --git a/src/evict/evict.h b/src/evict/evict.h index 600a39d2d..78338754d 100644 --- a/src/evict/evict.h +++ b/src/evict/evict.h @@ -137,6 +137,8 @@ struct __wt_evict { #define WT_EVICT_CALL_URGENT 0x4u /* Urgent eviction */ /* AUTOMATIC FLAG VALUE GENERATION STOP 32 */ +#define WT_EVICT_MAX_WORKERS 20 + /* DO NOT EDIT: automatically built by prototypes.py: BEGIN */ extern bool __wt_evict_page_urgent(WT_SESSION_IMPL *session, WT_REF *ref)
- is depended on by
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WT-13807 Change api_data.py config desc of how session slots are reserved for eviction and lsm workers
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- Needs Scheduling
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