JDK-7184772 : G1: Incorrect assert in HeapRegionLinkedList::add_as_head()
- Type: Bug
- Component: hotspot
- Sub-Component: gc
- Affected Version: 7u4
- Priority: P4
- Status: Resolved
- Resolution: Fixed
- OS: generic
- CPU: generic
- Submitted: 2012-07-17
- Updated: 2013-09-18
- Resolved: 2012-08-07
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| JDK 7 | JDK 8 | Other |
|---|---|---|
7u40Fixed  |
8Fixed |
hs24Fixed |
Description
The second assert in the following code from HeapRegionLinkedList::add_as_head():
if (_head != NULL) {
assert(length() > 0 && _tail != NULL, hrs_ext_msg(this, "invariant"));
from_list->_tail->set_next(_head);
} else {
assert(length() == 0 && _head == NULL, hrs_ext_msg(this, "invariant"));
_tail = from_list->_tail;
}
_head = from_list->_head;
is incorrect. The asert is checking that _head is NULL - when we already know it is NULL from negating the condition on the if-statment.
The assertion should be checking that _tail is NULL (the invariant is that both should be NULL).
Many thanks to Brandon Mitchell at Twitter for discovering and providing the fix for the issue.
Comments
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