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Overview
| Comment: | Add code to this branch to emit a log message after each cumulative second that the WRITER lock has been held. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | server-edition |
| Files: | files | file ages | folders |
| SHA3-256: |
a726d98122704e1e702cfa7ae61d6804 |
| User & Date: | dan 2017-05-22 08:01:58 |
Context
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2017-06-07
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| 15:55 | Add too/tserver.c - the implementation of a simple multi-threaded server designed for interactive testing of concurrency between connections used by different threads of the same process. check-in: 05b4fc43 user: dan tags: server-edition | |
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2017-05-22
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| 08:01 | Add code to this branch to emit a log message after each cumulative second that the WRITER lock has been held. check-in: a726d981 user: dan tags: server-edition | |
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2017-05-15
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| 19:32 | Avoid writer starvation by adding a RESERVED state to page locks. check-in: 9b7f8024 user: dan tags: server-edition | |
Changes
Changes to src/pager.c.
7546 7546 /* Close any rollback journal previously open */ 7547 7547 sqlite3OsClose(pPager->jfd); 7548 7548 7549 7549 rc = pagerOpenWal(pPager); 7550 7550 if( rc==SQLITE_OK ){ 7551 7551 pPager->journalMode = PAGER_JOURNALMODE_WAL; 7552 7552 pPager->eState = PAGER_OPEN; 7553 +#ifdef SQLITE_SERVER_EDITION 7553 7554 sqlite3WalServer(pPager->pWal, pPager->pServer); 7555 +#endif 7554 7556 } 7555 7557 }else{ 7556 7558 *pbOpen = 1; 7557 7559 } 7558 7560 7559 7561 return rc; 7560 7562 }
Changes to src/server.c.
89 89 ino_t st_ino; 90 90 }; 91 91 92 92 struct Server { 93 93 ServerHMA *pHma; /* Hma file object */ 94 94 int iClient; /* Client id */ 95 95 Pager *pPager; /* Associated pager object */ 96 - 96 + i64 nUsWrite; /* Cumulative us holding WRITER lock */ 97 + i64 iUsWrite; /* Time WRITER lock was taken */ 97 98 int nAlloc; /* Allocated size of aLock[] array */ 98 99 int nLock; /* Number of entries in aLock[] */ 99 100 u32 *aLock; /* Mapped lock file */ 100 101 }; 101 102 102 103 #define SERVER_WRITE_LOCK 3 103 104 #define SERVER_READ_LOCK 2 ................................................................................ 450 451 u32 n = v; 451 452 if( (v>>HMA_CLIENT_SLOTS)==p->iClient+1 ){ 452 453 n = n & ((1 << HMA_CLIENT_SLOTS)-1); 453 454 } 454 455 n = n & ~(1 << p->iClient); 455 456 if( __sync_val_compare_and_swap(pSlot, v, n)==v ) break; 456 457 } 458 + if( p->aLock[i]==0 ){ 459 + struct timeval t2; 460 + i64 nUs; 461 + gettimeofday(&t2, 0); 462 + nUs = (i64)t2.tv_sec * 1000000 + t2.tv_usec - p->iUsWrite; 463 + p->nUsWrite += nUs; 464 + if( (p->nUsWrite / 1000000)!=((p->nUsWrite + nUs)/1000000) ){ 465 + sqlite3_log(SQLITE_WARNING, 466 + "Cumulative WRITER time: %lldms\n", p->nUsWrite/1000 467 + ); 468 + } 469 + } 457 470 } 458 471 p->nLock = 0; 459 472 #if 1 460 473 return posixLock(p->pHma->fd, p->iClient+1, SERVER_READ_LOCK, 0); 461 474 #endif 462 475 return SQLITE_OK; 463 476 } ................................................................................ 564 577 do{ 565 578 v = *pSlot; 566 579 assert( serverWriteLocker(v)==p->iClient ); 567 580 n = v & ((1<<HMA_CLIENT_SLOTS)-1); 568 581 }while( __sync_val_compare_and_swap(pSlot, v, n)!=v ); 569 582 } 570 583 584 + if( pgno==0 ){ 585 + struct timeval t1; 586 + gettimeofday(&t1, 0); 587 + p->iUsWrite = ((i64)t1.tv_sec * 1000000) + (i64)t1.tv_usec; 588 + } 571 589 assert( rc!=SQLITE_OK || sqlite3ServerHasLock(p, pgno, bWrite) ); 572 590 return rc; 573 591 } 574 592 575 593 int sqlite3ServerHasLock(Server *p, Pgno pgno, int bWrite){ 576 594 u32 v = *serverPageLockSlot(p, pgno); 577 595 if( bWrite ){ 578 596 return (v>>HMA_CLIENT_SLOTS)==(p->iClient+1); 579 597 } 580 598 return (v & (1 << p->iClient))!=0; 581 599 } 582 600 583 601 #endif /* ifdef SQLITE_SERVER_EDITION */