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OCCI Oracle C++ Call Interface

OCCI Oracle C++ Call Interface. Krzysztof Nienartowicz DB Workshop January 29-31, 2002. Overview. Architectural overview Occi typical usage, development cycle Issues to solve, problems Tools, techniques used to understand OCCI internals. General Architecture overview.

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OCCI Oracle C++ Call Interface

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  1. OCCIOracle C++ Call Interface Krzysztof Nienartowicz DB Workshop January 29-31, 2002

  2. Overview • Architectural overview • Occi typical usage, development cycle • Issues to solve, problems • Tools, techniques used to understand OCCI internals

  3. General Architecture overview • Associative ODMG like access using Ref<> • OCCI is a wrapper on top of OCI and Oracle internal calls • Set of C++ base classes, utility classes • templates • binary libraries

  4. Architectural overview. cont. • OCCI is composed of ~ 25 classes + 30 classes of Oracle Data Cartridge Interface (ODCI) definitions for schema handling • Ref<> access and root PObject classes act as a interface with hidden implementation delegated to RefImpl and PObject binary packaged • plus utility classes to handle oracle native types • Connections, db environment

  5. Architectural overview. cont. • innerNode as a user type. N1,..,N10 are private innerNode_C members • Access via get, set or as a public ones, OTT dependent

  6. Architecture overview, cont. 2 • STL dependencies • Binary and string types represented as STL std::vectors and std::strings • May hit the performance if a conversion (due to type casting) is done under the hood • No difference between const and non-const access patterns

  7. Typical, application flow

  8. OCCI Development cycle • DDL driven, one must have DB schema defined first • Two main cycles with given approach • Schema definition, schema tuning phase • Standard 3gl object oriented methodologies for the latter phase

  9. OCCI Development cycle, 2 • Schema definition - DDL/SQL

  10. OCCI Development cycle, 3

  11. OCCI Development cycle, 4

  12. Occi current problems, issues, tweaks • Oracle production/bug fix cycle dependency • Ball on the Oracle side: • Small leaks escalation, cache settings dependent • Ref<> const, internal memory initialisation problems • Prefetching problems • Users’ responsibility to delete embedded objects • Unnamed exceptions thrown sometimes, segmentation faults instead of exceptions occur

  13. Bloating memory (cache?) problem • Memory consumption of a trivial, very small object linked list iteration • Appears for many accesses for certain cache settings • Memory growth is access related not accessed objects’ size related • Benchmarking consequences…

  14. Occi memory problems detection • “Unistd.h” sbrk(0) very helpful • mpatrol package • Mpatrol, mptrace, mprof • Dynamic hooks to the OS (libc, stdc++) memory calls with no code changes, recompilation on UX • Sophisticated memory monitoring, profiling with logging and post mortem analysis

  15. Mpatrol usage • Memory graphical profiling with mprof • Visual tracing with mptrace • Textual form, calls’ graph • Memory leaks, resizing, deleting, allocating stats

  16. mpatrol • Easier tracing down of inefficiencies, in example beneath, extracted dereferencing of the app object.

  17. Other mpatrol benefits MEMSET: memset (0x002240C8, 68 bytes, 0x00) [-|-|-] 0xFEE72F34 kghualloc+600 0xFED0B20C kohalmc+480 0xFED0B020 kohalc+1836 0xFEA0D63C kadlal+80 0xFEDACFC8 kopldsgen+40 0xFEA15DB0 kadgscval+228 0xFEA15614 kadattrget+4396 0xFE9A39C0 OCIAnyDataAttrGet+68 0x000A14A0 oracle::occi::Number occi::AnyDataImpl::getNumber()const+104 0x00064E58 void innerNode_C::readSQL(oracle::occi::AnyData&)+32 0x00064D20 void*innerNode_C::readSQL(void*)+192 0xFECF3750 kodpunp+3700 0xFED02794 kocdsun+460 0xFECF6F7C kocgpn2+2720 0xFECF64D4 kocgpn+80 0xFED32B48 OCIObjectPin+3872 0x00088F94 oracle::occi::PObject*oracle::occi::RefImpl::pin()+168 0x0005F204 innerNode*oracle::occi::Ref<innerNode>::operator->()+44 0x0005C37C long BenchApp<long>::CheckInnerCycle(…)+212 0x000578D0 void BenchApp<long>::DoRead()+720 0x0005738C int BenchApp<long>::Run()+52 0x0005F78C main+92 • Occi internals quasi–debugging, i.e. allows to understand occi-oci-oracle layering better

  18. Summary • The Ref<> associative access the main OCCI advantage in comparison to other methods • Waiting for the next release to proceed with benchmarks • Cache handling improvement • Bugs to be removed • Inconsistencies to be removed (i.e. ott naming) • For mpatrol check: http://www.cbmamiga.demon.co.uk/mpatrol

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