StackOverflowError in toString() of JSONObject

#1

Hello,

Sometimes, I get the following error when executing the method toString() of a JSONObject.
In order to investigate the problem, I reduced the Java heap size from 22000 to 20000, but this problem didn’t occur more often. I guess this size if enough.
I also increase the “Maximum size of thread stack (in blocks)” from 4 to 5, and the problem happens again. But I don’t know the meaning of this.
Also, I don’t know what means “Number of blocks in pool”. (currently 13).
The exception occurs at the line 1118 in JSONObject.class :slight_smile:
" StringBuffer sb = new StringBuffer("{");"

Exception in thread “slowRequestsThread” java.lang.StackOverflowError: EDC-1.2:E=-1
at com.is2t.tools.ArrayTools.@M:0x3f4e4f6c:0x3f4e4f84@
at java.lang.AbstractStringBuilder.@M:0x3f4ea250:0x3f4ea266@
at java.lang.AbstractStringBuilder.@M:0x3f4eb72c:0x3f4eb752@
at java.lang.StringBuffer.@M:0x3f4ea72c:0x3f4ea74e@
at org.json.me.JSONObject.@M:0x3f4ea004:0x3f4ea030@
at org.json.me.JSONObject.@M:0x3f4e4cc4:0x3f4e4dd0@
at org.json.me.JSONArray.@M:0x3f4ce108:0x3f4ce148@
at org.json.me.JSONArray.@M:0x3f4d5564:0x3f4d5596@
at org.json.me.JSONObject.@M:0x3f4e4cc4:0x3f4e4dd0@
at org.json.me.JSONObject.@M:0x3f4ea004:0x3f4ea08e@
at org.json.me.JSONObject.@M:0x3f4e4cc4:0x3f4e4dd0@
at org.json.me.JSONArray.@M:0x3f4ce108:0x3f4ce148@
at org.json.me.JSONArray.@M:0x3f4d5564:0x3f4d5596@
at org.json.me.JSONObject.@M:0x3f4e4cc4:0x3f4e4dd0@
at org.json.me.JSONObject.@M:0x3f4ea004:0x3f4ea08e@
at org.json.me.JSONObject.@M:0x3f4e4cc4:0x3f4e4dd0@
at org.json.me.JSONArray.@M:0x3f4ce108:0x3f4ce148@
at org.json.me.JSONArray.@M:0x3f4d5564:0x3f4d5596@
at org.json.me.JSONObject.@M:0x3f4e4cc4:0x3f4e4dd0@
at org.json.me.JSONObject.@M:0x3f4ea004:0x3f4ea08e@
at org.json.me.JSONObject.@M:0x3f4e4cc4:0x3f4e4dd0@
at org.json.me.JSONObject.@M:0x3f4ea004:0x3f4ea08e@
at com.otodo.hub.impl.request.RequestManagerImpl.@M:0x3f4e0124:0x3f4e0140@
at com.otodo.hub.impl.request.RequestManagerImpl.@M:0x3f4e5404:0x3f4e54c0@
at com.otodo.hub.impl.request.Request.@M:0x3f4c1a98:0x3f4c1aba@
at com.otodo.hub.impl.request.PairByAction.@M:0x3f4c18f0:0x3f4c19ae@
at com.otodo.hub.impl.request.PairByAction.@M:0x3f4c74ac:0x3f4c74c6@
at com.otodo.hub.impl.request.PairingRequest.@M:0x3f4c7350:0x3f4c7457@
at com.otodo.hub.impl.request.Request.@M:0x3f4e92ac:0x3f4e92b8@
at com.otodo.hub.impl.request.RequestManagerImpl$2.@M:0x3f4c1a88:0x3f4c1a96@
at java.lang.Thread.@M:0x3f4ee9f0:0x3f4eea08@
at java.lang.Thread.@M:0x3f4ee93c:0x3f4ee948@
at java.lang.Thread.@M:0x3f4ee9a8:0x3f4ee9b3@

Best regards

#2

Hello Benoit,

The stack overflow occurs when a thread stacks overpass the limitation. A function’s stack increase when going deeper in call (typically recursive calls), with functions parameters and local variables.

As you said the stack limitations are defined with two main parameters:

  • Maximum size of thread stack (in blocks): this is a max number of block that one stack can take
  • Number of blocks in pool: this is the total number of block that all the stacks will share

A quick solution, if you have enough memory will be to increase both the pool of blocks and max per stack.

As your SOE occurs when parsing a JSONObject, is your json big? Could you handle your json with streams (ej.library.iot.json#1.0.0)

Regards,