Aleksey Plekhanov created IGNITE-11911:
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Summary: GridToStringBuilder allocates redundant memory
Key: IGNITE-11911
URL: https://issues.apache.org/jira/browse/IGNITE-11911
Project: Ignite
Issue Type: Bug
Affects Versions: 2.7
Reporter: Aleksey Plekhanov
A lot of classes in Ignite uses {{GridToStringBuilder}} to implement their
{{toString()}} method. {{GridToStringBuilder}} uses thread local buffer to
generate string representation. This buffer extended on demand but never
shrank. On the final step {{GridToStringBuilder}} uses java {{StringBuilder}}
class to produce output string and uses own buffer size as {{StringBuilder}}
initial capacity. This leads to unnecessary memory allocation since we only
need to allocate memory for meaningful data, but not for all buffer.
Reproducer:
{code:java}
public void testSB() {
GridToStringBuilder.toString(C1.class, new C1(1_000_000));
GridToStringBuilder.toString(C1.class, new C1(100));
}
public class C1 {
private String f;
C1(int len) {
f = new String(new char[len]);
}
}
{code}
Here on the second line about 1 million chars StringBuilder will be allocated,
but only about 100 chars needed.
Problem code (SBLimitedLength.java:293):
{code:java}
StringBuilder res = new StringBuilder(impl().capacity() + tailLen + 100);
{code}
Here {{length()}} method can be used instead of {{capacity()}}
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