Virtuoso JDBC Transaction Simulation Program

Virtuoso JDBC Transaction Simulation Program

What

Java program to simulate Virtuoso Transaction Handling

Why

It is important to understand Virtuoso Transaction Handling in order to minimise locks and deadlocks in the database, which can adversely affect application performance and stability.

How

The MTSparqlTest2.java JDBC Transaction Simulation program can be compiled with the Virtuoso JDBC Driver (for the Java runtime in use) and run as follows:

javac -cp "./virtjdbc4.jar:." MTSparqlTest2.java   // Compile program
java -cp "./virtjdbc4.jar:." MTSparqlTest2 init    // Loads the test data into Virtuoso instance 
java -cp "./virtjdbc4.jar:." MTSparqlTest2         // Run the test

The program usage is the defined at the beginning of the source file which needs to be amended accordingly depending on what transaction mode or size of params (graphs, triples, threads etc) the test is to be run with:

 static String url = "jdbc:virtuoso://localhost:1111/charset=UTF-8/log_enable=0";
 static String uid = "dba";
 static String pwd = "dba";

 static int n_iterations = 100; //how many queries will be executed by thread
 static int def_tx_isolation = Connection.TRANSACTION_READ_COMMITTED;
 static int dml_tx_isolation = Connection.TRANSACTION_REPEATABLE_READ;
 static int select_tx_isolation = Connection.TRANSACTION_READ_COMMITTED;
 static int n_threads = 10;
 static int commitAfterNCalls = 4;  // commit after N DML queries

 static int n_graphs = 10;       // count of graphs
 static int n_g_triples = 10000; // count of triples per graph
 static int n_g_uniq_obj = 2;    // count of uniq objects per graph

 static int n_top_for_select = 100;
 static int BATCH_SIZE = 5000;

 static String dml_query =
                  "select * from (SPARQL define output:format 'JSON' \n"
                 +"PREFIX owl:<http://www.w3.org/2002/07/owl#> \n"
                 +"DELETE { GRAPH ?g { ?s ?p ?o } } \n"
                 +"INSERT { GRAPH ?g { ?s ?p <%s> } } \n"
                 +"WHERE \n"
                 +"{ \n"
                 +"    GRAPH ?g { \n"
                 +"              ?s ?p <%s> . \n"
                 +"              BIND(<%s> as ?o) . \n"
                 +"              FILTER (?p != owl:sameAs) \n"
                 +"            } \n"
                 +"}) as rdfview FOR UPDATE";

 static String select_query =
          "SPARQL SELECT ?s ?p ?o "
         +"WHERE { \n"
         +"   GRAPH `iri(??)` {\n"
         +"               ?s ?p ?o \n"
         +"                   }\n"
         +"      } ORDER BY ?s ?p ?o";

Sample output from program run:

[virtuoso@opllinux5 ~]$ java -cp "./virtjdbc4.jar:." MTSparqlTest2
.
.
.
Conn_16 >> iter[U]= 61   Time:3045 ms
Conn_38 >> iter[S]= 94   Time:3097 ms
Conn_0 >> iter[S]= 91   Time:1760 ms
Conn_20 ###Deadlock happened for DML query
Conn_20 Call rollback
Conn_20 End rollback Time:1 ms
Conn_20 >> iter[U]= 99   Time:1959 ms
Conn_46 >> iter[U]= 97   Time:2 ms
Conn_46 >> iter[U]= 98   Time:2 ms
Conn_46 >> iter[U]= 99   Time:1 ms
===================================
Conn_47   Time:2506 ms
Conn_48   Time:2654 ms
Conn_49   Time:2607 ms

    Exec Time:2870 ms
   Total Time:3130 ms
[virtuoso@opllinux5 ~]$

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