ASP.NET Web PDF Document Viewer/Editor Control Library

During garbage collection, the running program may be suspended since the collector may need to manipulate objects needed by its execution In particular, a garbage collector may adopt a strategy named copy collection that can move objects in memory, and during this process, the references may be inconsistent To avoid dangling references, the memory model adopted by the CLR requires that methods access the heap through object references stored on the stack, and objects in the heap are forbidden to reference data on the stack Data structures are the essential tool provided by programming languages to group values A data structure is rendered as a contiguous area of memory in which the constituents are available at a given offset from the beginning of the memory.

ssrs code 128 barcode font, ssrs code 39, ssrs fixed data matrix, winforms pdf 417 reader, winforms qr code reader, winforms upc-a reader, c# remove text from pdf, itextsharp replace text in pdf c#, winforms ean 13 reader, itextsharp remove text from pdf c#,

Each I/O and each consistent get requires an access to the buffer cache, and while it is true that reading data out of the buffer cache is faster than disk, it is also true that the buffer cache gets are not free and not totally cheap Each will require many latches of the buffer cache, and latches are serialization devices that will inhibit our ability to scale We can measure both the I/O reduction as well as latching reduction by running a PL/SQL block such as this: ops$tkyte%ORA11GR2> begin 2 for x in ( select empno from emp ) 3 loop 4 for y in ( select empename, astreet, acity, astate, azip 5 from emp, heap_addresses a 6 where empempno = aempno.

7 8 9 10 11 12 13

The actual layout of an object is determined by the compiler (or by the interpreter for interpreted languages) and is usually irrelevant to the program since the programming language provides operators to access fields without having to explicitly access the memory System programming, however, often requires explicit manipulation of memory, and programming languages such as C allow controlling the in-memory.

and emp.empno = x.empno ) loop null; end loop; end loop; end; /

PL/SQL procedure successfully completed. Here, we are just emulating a busy period and running the query some 45,000 times, once for each EMPNO. If we run that for the HEAP_ADRESSES and IOT_ADDRESSES tables, TKPROF shows us the following: SELECT EMP.ENAME, A.STREET, A.CITY, A.STATE, A.ZIP FROM EMP, HEAP_ADDRESSES A WHERE EMP.EMPNO = A.EMPNO AND EMP.EMPNO = :B1 call count ------- -----Parse 1 Execute 72073 Fetch 72073 ------- -----total 144147 cpu elapsed disk query current -------- ---------- ---------- ---------- ---------0.00 0.00 0 0 0 11.53 11.79 0 0 0 6.55 6.58 3641 722160 0 -------- ---------- ---------- ---------- ---------18.09 18.38 3641 722160 0 rows ---------0 0 288292 ---------288292

layout of data structures. The C specification, for instance, defines that fields of a structure are laid out sequentially, though the compiler is allowed to insert extra space between them. Padding is used to align fields at word boundaries of the particular architecture in order to optimize the access to the fields of the structure. Thus, the same data structure in a program may lead to different memory layout depending on the strategy of the compiler or the runtime, even in a language such as C where field ordering is well-defined. By default, the CLR lays out structures in memory without any constraint, which gives the freedom of optimizing memory usage on a particular architecture, though it may introduce interoperability issues if a portion of memory must be shared among the runtimes of different languages.1 Interoperability among different programming languages revolves mostly around memory layouts, since the execution of a compiled routine is a jump to a memory address. But routines access memory explicitly, expecting that data is organized in a certain way. In the rest of this chapter, we discuss the mechanisms used by the CLR to interoperate with external code in the form of DLLs or COM components.

Misses in library cache during parse: 0 Optimizer mode: ALL_ROWS Parsing user id: 286 (recursive depth: 1) Rows Row Source Operation ------- --------------------------------------------------4 NESTED LOOPS (cr=10 pr=0 pw=0 time=60 us cost=8 size=280 card=4) 1 TABLE ACCESS BY INDEX ROWID EMP (cr=3 pr=0 pw=0 time=0 us cost=2 siz ) 1 INDEX UNIQUE SCAN EMP_PK (cr=2 pr=0 pw=0 time=0 us cost=1 size=0 ) 4 TABLE ACCESS BY INDEX ROWID HEAP_ADDRESSES (cr=7 pr=0 pw=0 time=54 us ) 4 INDEX RANGE SCAN SYS_C0019080 (cr=3 pr=0 pw=0 time=3 us cost=2 size= ) ******************************************************************************** SELECT EMP.ENAME, A.STREET, A.CITY, A.STATE, A.ZIP FROM EMP, IOT_ADDRESSES A WHERE EMP.EMPNO = A.EMPNO AND EMP.EMPNO = :B1 call count ------- -----Parse 1 Execute 72073 Fetch 72073 ------- -----total 144147 cpu elapsed disk query current -------- ---------- ---------- ---------- ---------0.00 0.00 0 0 0 11.61 11.74 0 0 0 4.70 4.78 4863 437132 0 -------- ---------- ---------- ---------- ---------16.32 16.52 4863 437132 0 rows ---------0 0 288292 ---------288292

Misses in library cache during parse: 0 Optimizer mode: ALL_ROWS Parsing user id: 286 (recursive depth: 1)