[MNG-7899] Various memory usage improvements - ASF JIRA

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Details

Type: Improvement
Status: Open
Priority: Major
Resolution: Unresolved
Affects Version/s: 4.0.0-alpha-2
Fix Version/s: None
Component/s: Design, Patterns & Best Practices, Embedding, General, Logging
Labels:
None

Description

Some optimisations can be applied to the code to reduce the use of temporary objects.

Typical improvements identified are:

reduce scope of temporary objects creation to avoid creating when not needed. Example :

public String toString() {        
    StringBuilder sb = new StringBuilder(512);        
    if (isEmpty()) {            
        return "empty";        
    }        
    for (MetadataGraphVertex v : vertices) {
    .....

can be replaced by

public String toString() {        
    if (isEmpty()) {            
        return "empty";
    }        
    StringBuilder sb = new StringBuilder(512);
    for (MetadataGraphVertex v : vertices) {
    .....

Reuse StringBuilder objects in loops by setting its length to zero
Use the StringBuilder.append() with index to avoid String.substring(). Example:

int idx = resourceName.lastIndexOf('/');
buffer.append(idx < 0 ? resourceName : resourceName.substring(idx + 1));

can be replaced by

int idx = resourceName.lastIndexOf('/');
if (idx < 0) {
    buffer.append(resourceName);
} else {
    buffer.append(resourceName, idx + 1, resourceName.length());                    }

Replace dynamic string creation static constants when possible
Avoid creating temporary strings with + operator when the final destination can be used instead, like PrintStream.print() method
Avoir using StringBuilder.append() method and util method MessageUtils.a() when the final destination can be used instead, like PrintStream.print() method