https://gerrit.onap.org/r/c/cps/+/123682 we had to introduce a 'new' ObjectMapper to resolve issues with datatypes. The question now is if we should update the same ObjectMapper everywhere in the project or even across all CPS projects.
Object Mapper
Jackson
Jackson is tailored towards parsing larger files. According to cited benchmarks it is slower than GSON with large files and much slower with small files.
Although Jackson is slower in parsing in all use cases, we have a specific use case in which Jackson parser excels due to its ability to acknowledge the data type which it is parsing. For example in CpsDataPersistenceImpl.java in the toDataNode method, we use the Jackson Object mapper to parse fragment entity attributes to a map of objects. CPS-591 implemented a bug fix to change the parser from GSON to Jackson as GSON was reading integer values as Doubles https://gerrit.onap.org/r/c/cps/+/123682.
It is also widely known as the most popular JSON parsing library.
GSON
GSON is faster than Jackson mapper. However, as mentioned in the use case above, GSON is not capable of parsing well when it does not know the data type which it is mapping. It is possible to cast the incoming data to the correct datatype but it is not useful in the case where we do not know the incoming datatype. As such, in the use case mentioned above it is more practical to use the Jackson parser.
Legacy Code
The cited article also shows benchmarks from 2017 in which Jackson parser was out performing GSON in the large file category. We can surmise that there is a constant battle between these objectMappers and Jackson may begin out performing GSON again in the future. For example this article from 2019 with new benchmarks states that the difference between the different mappers is negligible, with Jackson mapper having a slight lead with larger files.
Test Results
| Parser | Read 40 characters | Write 40 characters | Read 100 characters | Write 100 characters | Read 1000 characters | Write 1000 characters | Issues |
|---|---|---|---|---|---|---|---|
| Jackson | 7.488 microseconds | 0.296 microseconds | 10.984 microseconds | 0.567 microseconds | 50.49 microseconds | 5.12 microseconds | |
| GSON | 0.509 microseconds | 0.531 microseconds | 0.818 microseconds | 1.332 microseconds | 8.212 microseconds | 14.884 microseconds | GSON parses all numerical values to Doubles and as such it unable to dynamically allocate the object type that it is parsing |
Resolution
It would make the most sense to use GSON as much as possible as it is the faster than Jackson. However the practicality of Jacksons parsing cannot be overlooked. Therefore it would make sense to use the Jackson parser in this scenario. We also don't want to have or create a Jackson mapper and GSON mapper object in the same file however as the memory cost is quite high.
- GSON parser should solely be used in a class where possible.
- In the case where the Jackson mapper is necessary, the Jackson mapper should be used in the whole class so that there is only one parser object created for a class.
CPS-NCMP
- CpsDataPersistenceServiceImpl.java is using two mapper objects, GSON and Jackson, should be just Jackson
- NetworkCmProxyInventoryController.java is using the Jackson mapper where the GSON could be used instead
- NetworkCmProxyDataServiceImpl.java is using the Jackson mapper where the GSON could be used instead
Temporal
- CpsDataUpdatedEventMapper.java is using Jackson mapper where GSON could be used instead
Independent Testing Output
TEST 1
Row Length: 20
Amount of Rows: 2
Total Characters:40
Sample 1 of 1000 for context:
{
"shtejaotq":743274541,
"kgemtnjax":835572493
}Parsing Jackson
Jackson Total Execution Time for 1000 Samples: 7488 milliseconds
Average Execution Time per Sample: 7.488 microseconds
Parsing GSON
GSON Total Execution Time for 1000 Samples: 509 milliseconds
Average Execution Time per Sample: 0.509 microseconds
COMPARISON
JACKSON GSON
{"yawjfhvyp":372757483 {"yawjfhvyp":3.72757483E8
"ylldgoxat":969019115} "ylldgoxat":9.69019115E8}TEST 2
Row Length: 20
Amount of Rows: 5
Total Characters:100
Sample 1 of 1000 for context:
{
"ghnnxacwg":627166312,
"weexbqxxz":187860979,
"vnazlwjxw":888464657,
"lefllbkav":680153916,
"qwwmuullq":956680572
}Parsing Jackson
Jackson Total Execution Time for 1000 Samples: 10520 milliseconds
Average Execution Time per Sample: 10.52 microseconds
Parsing GSON
GSON Total Execution Time for 1000 Samples: 850 milliseconds
Average Execution Time per Sample: 0.85 microseconds
COMPARISON
JACKSON GSON
{"lyfxouunw":236275535 {"lyfxouunw":2.36275535E8
"okhwigzvc":585267299 "okhwigzvc":5.85267299E8
"nahwamzec":104464991 "nahwamzec":1.04464991E8
"ijmlmqira":780085959 "ijmlmqira":7.80085959E8
"othqkndmv":960833419} "othqkndmv":9.60833419E8}TEST 3
Row Length: 20
Amount of Rows: 50
Total Characters:1000
Sample 1 of 1000 for context:
{
"wptqxblfb":553507548,
"nbaxtredu":324083139,
"vqijoaziu":144390721,
"nrwxqbgas":306788077,
"ogbdryyoj":104971927,
"gkfbdrkbk":537378619,
"lshdskcve":236309228,
"wtbpnxjew":554359094,
"uhmaenhuy":322770800,
"ysiwzhxiu":989652357,
"qpvpcbrvd":158784720,
"qzljjisii":855712766,
"ifcyebeni":770824879,
"mwjwjmwer":626375442,
"etbqaeboc":294862340,
"wwddrycum":747061501,
"ugahmwclb":382668205,
"hwgxefgfq":423926323,
"qrpzsnpxq":332204537,
"diltsosly":127063694,
"ojsnimjad":759601613,
"yvfldgicy":756794624,
"zpqlhzosx":861493871,
"opyuujuct":836421890,
"oezsrutkj":800198261,
"yohdudboz":145523060,
"wvzxkcrhm":690445487,
"nuykqqjaf":646580393,
"fmyuzacqr":321286835,
"cqvwhippk":361635443,
"ntkyveeyv":444123298,
"vkzeyelky":640545391,
"cqxvhhpzl":745212950,
"iywlqqrpl":466710234,
"owxlxezzx":325644550,
"cxtuhlccj":538982643,
"qriscgyzx":528896083,
"atgeacdce":134644427,
"ieiiysmej":992409710,
"rlfgmhqvw":975947788,
"nlywhmjfu":670148981,
"yhjndhnzn":889909995,
"scfkrsbxz":198224877,
"tuyfyfxmv":383221605,
"gnhazathn":405891282,
"hyhucemxu":324333145,
"wkicvnnhr":785344246,
"kkodozrmr":241548242,
"hjprcgaul":229512854,
"tpmydsvvj":725765670
}Parsing Jackson
Jackson Total Execution Time for 1000 Samples: 52106 milliseconds
Average Execution Time per Sample: 52.106 microseconds
Parsing GSON
GSON Total Execution Time for 1000 Samples: 8499 milliseconds
Average Execution Time per Sample: 8.499 microseconds
COMPARISON
JACKSON GSON
{"kvpbkfjhc":909199666 {"kvpbkfjhc":9.09199666E8
"zfhxzemfw":636239367 "zfhxzemfw":6.36239367E8
"ljxducldl":489368253 "ljxducldl":4.89368253E8
"zpdpwotfl":591944248 "zpdpwotfl":5.91944248E8
"wjiooqzia":482992080 "wjiooqzia":4.8299208E8
"iochjfkus":332831284 "iochjfkus":3.32831284E8
"uxnfdjojz":938890734 "uxnfdjojz":9.38890734E8
"xbltjaqew":299425690 "xbltjaqew":2.9942569E8
"hkjdmxxmb":962254859 "hkjdmxxmb":9.62254859E8
"fjmcgobhn":547992639 "fjmcgobhn":5.47992639E8
"orwzpzzmu":820807822 "orwzpzzmu":8.20807822E8
"rfdbekjcx":275097929 "rfdbekjcx":2.75097929E8
"uxxozjoih":338627736 "uxxozjoih":3.38627736E8
"cjlkfjjcq":448937027 "cjlkfjjcq":4.48937027E8
"uqnnirliu":276864552 "uqnnirliu":2.76864552E8
"lxceqgufg":689678773 "lxceqgufg":6.89678773E8
"adjltrxoz":822406043 "adjltrxoz":8.22406043E8
"rnwctlvde":489461099 "rnwctlvde":4.89461099E8
"ajyeaqtpm":736075494 "ajyeaqtpm":7.36075494E8
"enrwfbntn":315084877 "enrwfbntn":3.15084877E8
"nvwhgxcxw":823902435 "nvwhgxcxw":8.23902435E8
"ejjxpccwz":908806150 "ejjxpccwz":9.0880615E8
"veazdvefx":718686888 "veazdvefx":7.18686888E8
"eleirpwya":811890070 "eleirpwya":8.1189007E8
"pgexoohtk":447322823 "pgexoohtk":4.47322823E8
"mxhfkpqen":871899106 "mxhfkpqen":8.71899106E8
"iifipqvuw":139827220 "iifipqvuw":1.3982722E8
"fvnltlqqz":651683652 "fvnltlqqz":6.51683652E8
"wtizegpgx":912094992 "wtizegpgx":9.12094992E8
"xtunumvys":521832782 "xtunumvys":5.21832782E8
"qofahiuca":177980881 "qofahiuca":1.77980881E8
"ddwgkqroa":563486320 "ddwgkqroa":5.6348632E8
"khgummffv":566546040 "khgummffv":5.6654604E8
"embvwgzxc":622414218 "embvwgzxc":6.22414218E8
"twjmhskgi":464054761 "twjmhskgi":4.64054761E8
"zntblffps":297389465 "zntblffps":2.97389465E8
"csdabfnfd":830710612 "csdabfnfd":8.30710612E8
"miofuwofz":386871027 "miofuwofz":3.86871027E8
"zgkzlkncq":675690367 "zgkzlkncq":6.75690367E8
"ghysxtjcm":499019987 "ghysxtjcm":4.99019987E8
"yixisblvx":287911842 "yixisblvx":2.87911842E8
"cvzmszwrj":880215017 "cvzmszwrj":8.80215017E8
"ghxqtrkaj":569935571 "ghxqtrkaj":5.69935571E8
"xnqnpdlzv":654646769 "xnqnpdlzv":6.54646769E8
"mujytcjkn":695265416 "mujytcjkn":6.95265416E8
"queybotdd":507165384 "queybotdd":5.07165384E8
"ikboejdrj":492564702 "ikboejdrj":4.92564702E8
"mlcicbvki":909981316 "mlcicbvki":9.09981316E8
"kakwtlukw":839042731 "kakwtlukw":8.39042731E8
"dacnlsxxc":636897263} "dacnlsxxc":6.36897263E8}