bigbuger opened a new issue #7668:
URL: https://github.com/apache/shardingsphere/issues/7668
Engine parsing the first SQL is particularly slow. This may be caused by a
engine initialization take long time.
My test code:
``` java
private static SQLParserEngine getParseEngine() {
return SQLParserEngineFactory
.getSQLParserEngine("MySQL");
}
private static void testParse(final List<String> sqlList) throws
JsonProcessingException {
final int testCount = 1000;
final SQLParserEngine parseEngine = getParseEngine();
final List<Map<String, Object>> result =
Lists.newArrayListWithExpectedSize(sqlList.size());
for (final String sql : sqlList) {
System.out.println("test for sql:" + sql);
final Map<String, Object> sqlTestResult = new HashMap<>(5);
long min = Long.MAX_VALUE;
long max = 0;
long total = 0;
long first = 0;
for (int i = 0; i < testCount; i++) {
final StopWatch stopWatch = new StopWatch();
stopWatch.start();
final SQLStatement sqlStatement = parseEngine.parse(sql,
false);
stopWatch.stop();
final long timeMillis = stopWatch.getTotalTimeMillis();
if (i == 0) {
first = timeMillis;
}
min = Math.min(timeMillis, min);
max = Math.max(timeMillis, max);
total += timeMillis;
}
sqlTestResult.put("sql", sql);
sqlTestResult.put("first", first);
sqlTestResult.put("min", min);
sqlTestResult.put("max", max);
sqlTestResult.put("average", total * 1.0 / testCount);
sqlTestResult.put("testCount", testCount);
result.add(sqlTestResult);
}
final ObjectMapper mapper = new ObjectMapper();
System.out.println("test result:");
System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result));
}
```
Test result:
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